Field guide

how to benchmark before you buy.

Every test worth running, in the order that finds faults fastest. What to install, what to click, what number to expect, which way that number should point, and what a bad one actually means. Written for the ten minutes you get with somebody else’s machine — and the four hours you get with your own.

22 sections14 category guides60+ tools, every one linked3 checklists that save your ticksUpdated September 2026

Contents22 sections

Part 0

Before you start

Fifteen minutes of setup is the difference between a number that settles an argument and a number that starts one.

Read this bit

Start here

Three situations bring people to a page like this. Find yours, and skip to the part that is actually about you.

AYou are meeting a seller in an hour

Take the fifteen-minute checklist, then read steps 01 to 03. Those three catch almost every fault you can find without a lab.

To the checklist →BIt has arrived and the return window is ticking

Do the whole thing, in order, this week. Most real faults need heat and time before they show themselves, and a refund has a deadline.

To the full bench →CYou are selling, or negotiating

Numbers do the arguing for you. Learn what each shortfall is worth in money, and what to put in a listing so the price holds.

To the money →

What a benchmark can honestly tell you

Whether the part is what the ad said. A relabelled card, a downclocked laptop chip and a single stick of RAM sold as a matched pair all show up inside two minutes.
Whether it performs like other examples of itself. This is the whole game. One score means nothing; the same score next to five thousand other people’s scores means everything.
Whether it stays stable when it is hot. Faults hide at idle.
Whether it is being held back by heat, a power limit, a bad mount, a wrong slot or a stale driver — all of which are fixable, and all of which are worth a discount.

What it cannot

How long it will last. Nothing you can run in an afternoon predicts a failure two years out. Health data narrows the odds; it does not settle them.
Whether a graphics card was mined on. There is no counter for this and anyone selling you a detection method is guessing. What you can check is the state it is in now — fans, pads, temperatures, artifacts — which is the part that actually affects you.
Whether the part suits you. That is a specification question, not a benchmark question. A perfectly healthy card that is too slow for your monitor is still the wrong purchase.

The one rule

A benchmark number is a comparison and nothing else. It compares this machine against other machines, or against itself last month. Quoted alone, with no baseline and no conditions attached, it is decoration. Everything below exists to make your comparison a fair one.

The pointer used throughout this page

Every table on this page marks which way a number is supposed to move. Two of these are not about better or worse at all — they are about right or wrong.

Higher is better▲Higher is betterLower is better▼Lower is betterMust be zero∅Must be zeroMust match the spec=Must match the spec

Router

Find what you are buying

Everything the marketplace lists, and where this guide answers it. The eight steps below cover any machine with a computer in it; these are the parts that need something the eight steps do not say.

In progress

The categories marked as being written are the ones still to come. Each will get the same treatment: what to run, what the number should say, when to walk away, and what every fault is worth off the asking price.

Method

Ten rules that make a number mean something

Benchmarking badly is worse than not benchmarking, because it hands you a number you now believe. These ten rules are the whole of the methodology.

The method, in ten lines

Change one thing at a time. New driver, new RAM speed, new fan curve — one of them, then re-run. Change two and you have learned nothing about either.
Three runs. Take the median. Bin the first one. The first run of anything is compiling shaders, warming caches and filling RAM. It is always the odd one out, and quoting it is how people accidentally lie.
Write down the setup, not just the score. Resolution, preset, driver version, RAM speed, power plan, benchmark version, room temperature. A score without its conditions cannot be compared to anything, including your own score next month.
Let it get hot before you believe it. A cold machine flatters itself for about ninety seconds. Every part that matters boosts hard, heats up, and settles lower. The settled number is the real one, so run for ten minutes, not one.
Write down the room temperature. Every thermal result on earth is meaningless without it. A 75°C CPU in a 19°C room and a 75°C CPU in a 31°C room are two very different coolers.
Close everything, then reboot. Browser, chat overlays, RGB software, cloud sync, game launchers, the recording tool you forgot about. Then reboot, because half of them come back.
Never compare across versions, resolutions or presets. Cinebench 2026 deliberately rescaled its scores and they do not compare to the 2024 numbers still filling search results. Same for a 1080p score against a 1440p one. If the two runs are not identical in every setting, they are not comparable.
Watch the clocks, not the temperature. Modern chips are designed to sit at their thermal limit. The limit is not the fault. The fault is the clock speed falling to stay there — so log frequency alongside temperature and read them together.
If two runs differ by more than about 3%, your bench is wrong. Not the hardware. Something is still running, the machine is still hot from the last run, or a power setting is fighting you. Fix that before you draw a conclusion.
Finish with something real. Synthetic scores are for comparison; they are not the reason you bought a computer. The last test should always be the game you play or the job you do.

Worth knowing

One honest number beats ten impressive ones. If you only ever do two things, do these: run a ten-minute sustained load with the clocks logged, and play something real for an hour with an overlay on. That pair finds more genuine faults than an afternoon of synthetic scores.

Preparation

Setting a clean bench

Do this once, properly, and every result after it is trustworthy. Skip it and you will spend the evening chasing a 12% deficit that turns out to be a browser tab.

25 minutesOnce per machineDo it before any score

Get these first

HWiNFO64FreeWindowsEvery sensor on the machine, plus CSV logging. The one tool to install first.CPU-ZFreeWindowsExact CPU model and stepping, and the memory tab that exposes channel count and timings.GPU-ZFreeWindowsGraphics card identity, VBIOS, PCIe link width, and a counterfeit-card check.CrystalDiskInfoFreeWindowsSMART data: drive health, power-on hours, total bytes written, link speed.Display Driver UninstallerFreeWindowsStrips a graphics driver back to nothing, so your numbers are not someone else’s leftovers.

Before the first run

Install the four information tools first. HWiNFO for sensors and logging, CPU-Z and GPU-Z for identity, CrystalDiskInfo for drive health. None of them change anything; they just tell you what you are holding.
Clean the graphics driver. If the machine came from someone else, or has been through a card swap, run DDU in safe mode and install the current driver fresh. Half of all mystery performance deficits are a driver stack with three generations layered on top of each other.
Update Windows, then pause updates. Nothing ruins a four-hour soak test like a restart at hour three.
Set the power plan. Balanced or High performance, sleep and screen-off disabled for the session. On a laptop: plugged in, on the mains profile, and then again on battery later — those are two different machines and both matter.
Go into the BIOS. Enable XMP or EXPO so the RAM runs at the speed printed on it. Enable Resizable BAR. Leave everything else at stock, including any overclock the previous owner left behind — you are measuring the part, not their tuning.
Close the lot and reboot. Overlays, RGB utilities, browsers, launchers, cloud sync. Then check Task Manager sits near idle before you start.
Start HWiNFO logging to CSV and make a folder for screenshots. You want evidence, not memories, if this turns into a return or a dispute.
Note the room temperature and leave the door shut. Every thermal number from here is a delta from this.

Laptops

Run everything twice: once plugged in, once on battery. Manufacturers routinely cut the power limit in half on battery, and a machine that scores well on the mains can lose 40 to 60% of its performance unplugged. If you never mentioned that you would be using it unplugged, nobody was lying to you — but it is still the number you care about.

For meet-ups

Put the portable builds of HWiNFO, CPU-Z, GPU-Z, CrystalDiskInfo, CrystalDiskMark and 7-Zip on a USB stick before you leave. None of them need installing or an internet connection, and you will not be given the Wi-Fi password.

Part 1

The eight steps

In this order on purpose. Identity and health are free, fast, and rule out the expensive mistakes before you have spent an hour scoring a part that was never the right part.

Step one

Is it what they said it was?

Before performance, provenance. Every year people pay flagship money for a relabelled mid-range card, a laptop chip in a desktop socket, or half the RAM they were promised. All three take under two minutes to catch.

10 minutesWorks offlineDo this first, always

Get these first

GPU-ZFreeWindowsGraphics card identity, VBIOS, PCIe link width, and a counterfeit-card check.CPU-ZFreeWindowsExact CPU model and stepping, and the memory tab that exposes channel count and timings.HWiNFO64FreeWindowsEvery sensor on the machine, plus CSV logging. The one tool to install first.CrystalDiskInfoFreeWindowsSMART data: drive health, power-on hours, total bytes written, link speed.

The two-minute identity sweep

Open GPU-Z. Read the Name field. If a counterfeit is detected it prefixes the name with [FAKE] and swaps the vendor logo for a warning triangle. Then check memory size and type against what the model is supposed to ship with, and check the GPU codename — a card sold as one thing with a different die underneath is the classic marketplace fraud.
Run GPU-Z’s render test (the question-mark button next to Bus Interface). Cards idle at a reduced link width to save power, so the only reading that means anything is the one under load. A desktop card in the primary slot should report x16.
Open CPU-Z. Confirm the exact specification string, not the marketing name. Then open the Memory tab: channel count, size, and DRAM frequency. Double the frequency for the DDR number — 3000 MHz shown is DDR5-6000.
Open the SPD tab and click through each slot. This tells you how many sticks are fitted, in which slots, and whether they are a matched set. Two different part numbers is not a fault, but it is a fact worth knowing and worth money.
Open CrystalDiskInfo. Model, firmware and — critically — the transfer mode, which shows the PCIe generation and lane width the drive negotiated against what it supports.
Photograph the serials and check them against the ad, the box and any warranty record. Then check the manufacturer’s warranty page while you are still standing there.

What to read, and what it should say

Metric	Which way	What it tells you	Healthy looks like
GPU-Z › Name	Must match the spec	The card read from the silicon rather than the sticker.	Exactly the model advertised, with no [FAKE] prefix and no warning triangle.
GPU-Z › Memory Size / Type	Must match the spec	How much video memory is actually fitted, and which kind.	The capacity and memory type that model shipped with. Check it against TechPowerUp’s database, not the seller.
GPU-Z › Bus Interface, under load	Must match the spec	The PCIe lanes the card is really getting.	x16 for a desktop card in the top slot. x8 or x4 means the wrong slot, a shared lane, a riser, or a damaged connector.
CPU-Z › Memory › Channel #	Must match the spec	Whether the RAM is running in dual channel.	Dual on a mainstream desktop. Single channel costs 10 to 20% in games and is the most common silent downgrade in prebuilts.
CPU-Z › Memory › DRAM Frequency	Must match the spec	The speed the memory is actually running at, not the speed on the box.	Half the rated DDR number. If it reads 1067 MHz on a DDR5-6000 kit, XMP or EXPO was never switched on.
CrystalDiskInfo › Transfer Mode	Must match the spec	The PCIe link the drive negotiated, next to the one it supports.	Both halves the same. A Gen4 drive linked at Gen3 x2 is in the wrong slot and losing most of its speed.

Walk away if

GPU-Z flags the card, or the codename is not the die that model uses.
Serial numbers are removed, sanded, or do not match between the part, the box and the ad.
The seller will not let you run a two-minute information tool on a machine they claim works fine.
A graphics card cannot hold x16 under load and there is no explanation for it.
A laptop reports a different CPU or GPU to the one in the listing — check for mobile parts sold under desktop names.

Step two

Will it still be alive in six months?

Performance is what you are paying for. Health is what you are gambling on. Drives, batteries and memory all keep a running record of their own decline, and it is free to read.

20 minutesPlus an overnight testThe cheapest insurance here

Get these first

CrystalDiskInfoFreeWindowsSMART data: drive health, power-on hours, total bytes written, link speed.MemTest86Free tierBootable USBTests RAM outside the OS, so nothing is in the way. The one to run overnight.memtest_vulkanFreeWin / LinuxTests video memory for errors specifically. Catches bad VRAM that games only stutter on.OCCTFree tierWindowsPower, 3D, VRAM and memory tests that detect calculation errors, not just crashes.BatteryInfoViewFreeWindowsLive battery wear and charge/discharge rate without generating a report.

The health pass

SMART data for every drive. CrystalDiskInfo, one tab per drive. Read the health status first, then the raw values in the table below. This is the single most informative screen in the whole guide and it takes ten seconds.
Compare total writes against the drive’s rated endurance. Look up the TBW figure for that exact model. A 600 TBW drive with 40 TB written has barely started. The same drive with 500 TB written is a different purchase at a different price.
Test the video memory. Run memtest_vulkan, or OCCT’s VRAM test, for fifteen minutes. Bad VRAM does not usually crash — it stutters, corrupts textures and drops frames in ways people blame on drivers for months.
Test the system memory overnight. MemTest86 from a USB stick if you can, because it runs outside the operating system with nothing else in the way. In Windows, TestMem5 or OCCT’s memory test will do. The only acceptable error count is zero.
Open Reliability Monitor (search it in the Start menu) and read the last few months. Repeated hardware errors, unexpected shutdowns and driver crashes are a history the seller did not have to volunteer.
Check Event Viewer for WHEA errors after your first day of testing. WHEA logs a hardware error the machine survived — which is exactly the thing that is about to stop surviving.
Look at it under a torch. Bulging or leaking capacitors, corrosion, bent socket pins, cracked solder around the PCIe slot, and any browning or melting on a 12VHPWR power connector.

SMART and health values that decide a purchase

Metric	Which way	What it tells you	Healthy looks like
Health Status	Must match the spec	CrystalDiskInfo’s overall verdict on the drive.	Good, at or near 100%. Caution means the drive has already started reporting failures — treat it as a drive with no future.
Reallocated Sectors Count	Must be zero	Sectors the drive has permanently given up on and mapped out.	Zero. On a hard drive, any non-zero value means the surface has started to fail, and it does not stop.
Current Pending Sector Count	Must be zero	Sectors that failed a read and are waiting to be judged.	Zero. This one is worse than reallocated — those are pending data loss, not past it.
Percentage Used (NVMe)	Lower is better	How much of the flash’s rated write endurance has been consumed.	Under 10% on a drive being sold as lightly used. 100% is the end of the warranty, not the end of the drive — but it is the end of the price.
Total Host Writes / TBW	Lower is better	Everything ever written to the drive.	Under about a third of the model’s rated TBW. Compare, do not guess — ratings range from 150 TB to well over 1,000 TB.
Power On Hours	Lower is better	Time powered up, which is not the same as time worked.	8,760 hours is one year switched on. It matters enormously on a hard drive and much less on an SSD, where writes are the real clock.
Unsafe Shutdown Count	Lower is better	Power lost mid-write.	A handful is normal life. Hundreds points at a failing power supply or a machine that crashes regularly — ask which.
Memory / VRAM errors	Must be zero	Bit errors found under a memory test.	Zero, always. One error is a fault; there is no acceptable non-zero number here.
Battery full charge vs design capacity	Higher is better	How much of the original battery is left.	Above 85% is healthy. 80 to 85% is normal wear. Below 80% is a replacement you are paying for, so price it in.

Careful

A high power-on-hours count on an SSD is not, by itself, bad news. A drive that has been switched on for 20,000 hours but only written 15 TB has spent its life idling in a machine that was never off. Read hours and writes together; either one alone will mislead you.

Walk away if

Any reallocated or pending sectors on a drive that is part of the price.
A single memory error, in any test, at stock settings.
Health status showing Caution, however good the speed numbers look.
Browning, melting or a burnt smell at any power connector.
Bulging capacitors, or corrosion anywhere on a board.
Reliability Monitor showing a wall of hardware errors that the seller described as “runs perfectly”.

Step three

The processor

Two numbers matter and they are not interchangeable. Single-core speed is what games and almost every everyday application feel. Multi-core is what rendering, compiling and exporting live on. A chip can be excellent at one and ordinary at the other.

20 minutes10-minute loop is the real testWatch clocks, not temperature

Get these first

Cinebench 2026FreeWin / MacThe standard sustained CPU render test, single and multi-core, with a timed loop mode.Geekbench 6Free tierEverythingShort mixed-workload CPU score. The only benchmark that compares a phone, a Mac and a PC.7-Zip benchmarkFreeWindowsBuilt into 7-Zip (Tools › Benchmark). Runs offline, in 60 seconds, on a stranger’s PC.y-cruncherFreeWin / LinuxPi calculation. Doubles as the harshest realistic CPU and memory stability test there is.Prime95FreeWin / Mac / LinuxSmall FFT torture test — worst-case heat, for proving a cooler rather than scoring a chip.Blender BenchmarkFreeWin / Mac / LinuxReal render workload for CPU and GPU, with a public results database to compare against.

Run it in this order

Cinebench, single-core then multi-core. Three runs of each, median recorded. This is the number everyone quotes and the one with the deepest comparison pool.
Cinebench again, on a 10-minute loop, with HWiNFO open next to it. Now compare the all-core clock in the final minute against the first. That comparison is the actual test — the score just tells you where you started.
Geekbench for a second opinion from a completely different workload mix. If Cinebench and Geekbench disagree about how this chip ranks, that is information, not an error: one is sustained rendering, the other is short bursts of mixed work.
7-Zip’s built-in benchmark (Tools › Benchmark) when you are on somebody else’s machine with no internet. Sixty seconds, no install, and the MIPS figure is comparable across machines.
y-cruncher if you want the harshest realistic test there is. It hammers the processor and the memory controller together, which is where most instability actually lives, and it reports errors rather than just crashing.
Prime95 Small FFT only to prove a cooler. It is unrealistic on purpose — the heat it makes is worse than anything you will ever run — so treat it as a thermal ceiling test, never as a performance score.

Processor numbers, and which way they should point

Metric	Which way	What it tells you	Healthy looks like
Cinebench multi-core	Higher is better	Sustained throughput with every core loaded.	Within about 5% of the public median for that exact chip. More than 10% down needs an explanation.
Cinebench single-core	Higher is better	Per-core speed — what games and most applications actually feel.	Within about 5% of median. This one barely moves with cooling, so a low result usually means the wrong power profile or a wrong chip.
Effective clock, all cores, minute 10	Higher is better	The frequency it can genuinely hold once it is hot.	Close to the first minute. A few hundred megahertz of settle is normal; a fall of a gigahertz is a cooling problem.
Loop run 1 vs final run	Higher is better	How much score is lost to heat soak over ten minutes.	Within about 3%. A steadily falling score across the loop is a cooler that cannot keep up.
Package power under load	Must match the spec	Watts the chip is allowed to draw.	The rated limit for that chip and board. Well under it, with clocks low, means a power limit is set — often deliberately, by whoever owned it before you.
Core temperature under sustained load	Lower is better	How hot it runs, which is less damning than people think.	Below the limit for that chip. Recent Ryzen sitting at 95°C and recent Intel at 100°C is designed behaviour, not a fault — read the clocks to find out whether it is costing you anything.
Thermal throttling flag (HWiNFO)	Must be zero	Whether the chip is actively cutting clocks to survive.	No, on a desktop with adequate cooling. Yes on a thin laptop is common and is the reason its sustained score is low.
7-Zip total rating (MIPS)	Higher is better	Compression throughput. Runs offline in a minute.	In line with the same chip elsewhere. Good for meet-ups, weak for fine comparisons — it is very sensitive to memory speed.
y-cruncher errors	Must be zero	Computation errors under a combined CPU and memory load.	Zero. Errors here almost always mean memory or memory-controller instability rather than a bad core.

Read this before panicking about temperature

Modern processors are designed to run to their thermal limit and stop there. A Ryzen 7000 or 9000 chip pinned at 95°C during Cinebench is doing exactly what AMD built it to do, and recent Intel parts behave the same way at 100°C. The question is never “is it hot”. The question is what clock speed is it holding while it is hot, and whether that clock is where that chip should be. Log both, read them together, ignore the temperature on its own.

Buying a used 13th or 14th generation Intel chip

Some Core i7 and i9 parts from those two generations suffered permanent degradation from excessive voltage before the microcode was fixed. A degraded chip is stable until it is not: it passes a short benchmark and then crashes in shader compilation or under a long load. If you are buying one, insist on the current BIOS being installed, then run a long y-cruncher or Prime95 session before you accept it — and check what warranty is left, because Intel extended it on the affected parts.

Walk away if

Score more than 10% below median with no power limit or thermal reason.
All-core clock collapsing within the first two minutes of a loop.
Any error at all in y-cruncher or Prime95 at stock settings.
Crashes or reboots during a load test, at any temperature.
A seller who will not let the machine run for ten unbroken minutes under load.

Step four

The graphics card

The most expensive part, the most faked part, and the one where a bad example still runs — just badly, hot, and with textures that flicker. Score it, then heat it, then look for artifacts.

40 minutesArtifacts need time to appearHotspot delta is the tell

Get these first

3DMarkFree tierWindowsThe GPU benchmark with the largest comparison database. Free tier covers Time Spy and Steel Nomad.Unigine SuperpositionFree tierWin / LinuxRepeatable GPU score plus a looping stress mode that makes artifacts obvious on screen.GPU-ZFreeWindowsGraphics card identity, VBIOS, PCIe link width, and a counterfeit-card check.MSI KombustorFreeWindowsLoops a 3D scene with automatic artifact detection — the dying-VRAM test.memtest_vulkanFreeWin / LinuxTests video memory for errors specifically. Catches bad VRAM that games only stutter on.OCCTFree tierWindowsPower, 3D, VRAM and memory tests that detect calculation errors, not just crashes.

The graphics run

3DMark Time Spy and Steel Nomad. Both are in the free tier on Steam. Record the Graphics score separately from the overall score — the overall figure blends in the processor, so a strong card in a weak system looks worse than it is.
Superposition at the preset your card is aimed at, for a second data point from a different engine. Then leave it looping for half an hour: its dense scene makes artifacts obvious the moment they appear.
Kombustor with artifact detection on, or OCCT’s 3D test, which reports calculation errors rather than only crashing. That distinction matters: a card can be quietly producing wrong pixels for months without ever falling over.
memtest_vulkan for the video memory. Failing VRAM is the single most common fault in ex-mining and heavily used cards, and it presents as stutter rather than as a crash.
Watch GPU-Z’s sensors the whole time. Core clock, memory clock, hotspot temperature, memory junction temperature, fan speed, and PerfCap Reason — which tells you in one word why the card is not going faster.
Finish in a real game with a built-in benchmark, three passes, first pass discarded. Cyberpunk 2077, Shadow of the Tomb Raider, F1, Forza Horizon and Black Myth: Wukong all have repeatable built-in runs.

Graphics numbers that decide it

Metric	Which way	What it tells you	Healthy looks like
3DMark Graphics score	Higher is better	The card on its own, with the processor factored out.	Within 5% of the median for that model in 3DMark’s own result search. Use Graphics score, never the overall score, to judge a card.
Core clock under sustained load	Higher is better	The speed the card holds once it is properly hot.	Near its rated boost, holding steady. Sawtoothing between high and low is a power or thermal limit being hit repeatedly.
Hotspot minus edge temperature	Lower is better	The gap between the hottest point on the die and the average across it.	Around 10 to 15°C. Past 20 to 25°C the thermal paste has dried out or the cooler is badly mounted — fixable for the price of paste, and worth negotiating over.
Memory junction temperature	Lower is better	How hot the video memory itself is running. GDDR6X cards especially.	Comfortably under 95°C. At 105 to 110°C it throttles, and cards that live there have thermal pads that need replacing.
PerfCap Reason (GPU-Z)	Must match the spec	One word for why the card is not clocking higher.	Pwr or Util is normal and healthy. Thrm under an ordinary load means heat is costing you performance. VRel or VOp on a stock card is worth asking about.
Artifacts in a 30-minute loop	Must be zero	Flickering triangles, coloured speckles, corrupted textures.	None. A single artifact is a failing card; there is no such thing as an acceptable amount.
VRAM errors	Must be zero	Bit errors in video memory under a dedicated test.	Zero. This is the fault that gets sold as “just needs a driver reinstall”.
Fan speed and noise at 100%	Must match the spec	Whether the cooler still works as built.	All fans spin, none rattle or grind, and the RPM matches what the model is rated for. Fans are the part of a card that genuinely wears out.

On ex-mining cards

There is no reliable way to detect mining from software, and the honest picture is more nuanced than the panic suggests: a card that ran undervolted at a constant temperature for a year may be in better shape than one that spent that year in thermal cycles inside an unfiltered gaming case. What mining genuinely costs you is fan bearings, thermal pads and paste — all wear items, all replaceable, all worth money off. So stop trying to prove its history and test its present: temperatures, hotspot delta, fan noise, memory errors, artifacts. Do check GPU-Z’s BIOS version, though, since mining cards are often flashed.

If the seller only gives you five minutes

Superposition on a medium preset plus a GPU-Z sensor tab tells you most of it. You get a score to compare, a hotspot delta, a memory temperature and a PerfCap reason — four of the eight rows above — inside five minutes and one download.

Walk away if

Any artifact, ever, at stock clocks.
Hotspot delta above 25°C, unless the price already assumes a repaste.
Graphics score more than 10% below median with temperatures that look fine.
Driver timeouts, black screens or a crash to desktop during a stress loop.
Browning, melting or a loose fit at the 12VHPWR or 12V-2x6 power connector on a recent high-end card.
A card that has clearly been apart — stripped screws, fingerprints on the die, paste squeezed onto the PCB — sold as untouched.

Step five

Memory

The cheapest part to get wrong and the most annoying to diagnose. Half of all “unstable PC” complaints are memory running at a speed it cannot hold, or one stick where there should be two.

15 minutes to checkOvernight to proveZero errors or nothing

Get these first

CPU-ZFreeWindowsExact CPU model and stepping, and the memory tab that exposes channel count and timings.AIDA64 ExtremeTrialWindowsThe memory bandwidth and latency benchmark everyone quotes. Trial period is enough.TestMem5FreeWindowsFinds memory errors fast — usually inside an hour with the right config.MemTest86Free tierBootable USBTests RAM outside the OS, so nothing is in the way. The one to run overnight.Karhu RAMTestPaidWindowsThe gold standard for coverage-based memory testing. Worth it if you tune RAM often.HCI MemTestFree tierWindowsOld, ugly, and still trusted. Free version runs one instance per thread.

Check the configuration first, the speed second

CPU-Z Memory tab. Channel count, total size, DRAM frequency, and the four primary timings. This one screen answers most questions.
Confirm XMP or EXPO is on. If the frequency reads at the JEDEC default — 1067 MHz for a DDR5-6000 kit, 1200 MHz for DDR4-2400 — the memory is running far below what it was sold as. Enable the profile in BIOS and re-run everything above it.
Check which slots are populated. Two sticks belong in slots 2 and 4 on almost every mainstream board. In the wrong pair they may run single channel or refuse to post at rated speed.
Run the memory benchmark in AIDA64 for read, write, copy and latency. Note all four; latency moves independently of bandwidth and is what games feel.
Then prove it is stable. TestMem5 with a strict config finds most errors within an hour. MemTest86 from a USB stick overnight is the thorough version, because it runs with the operating system out of the way.
Any error means stop. Then work out whether it is the sticks, the profile or the memory controller: re-test at JEDEC defaults, and one stick at a time.

Memory numbers

Metric	Which way	What it tells you	Healthy looks like
Channel count	Must match the spec	How many memory channels are actually in use.	Dual on mainstream desktops and most laptops. Single channel costs 10 to 20% in games and far more on integrated graphics.
DRAM frequency × 2	Must match the spec	The real transfer rate.	The rated speed of the kit. Anything lower means the profile is off, the board cannot hold it, or the kit is not what it says.
Read / write / copy bandwidth	Higher is better	How much data the memory can move.	In line with the same kit and platform elsewhere. Roughly half the expected figure is the signature of single-channel operation.
Memory latency (ns)	Lower is better	How long a request waits. What games actually feel.	Compare against the same platform and speed grade. Latency well above typical usually means loose timings or a fallback profile.
Errors in any memory test	Must be zero	Bit errors under load.	Zero. One error is a fault. There is no threshold and no “close enough” here.
Total capacity	Must match the spec	What the operating system can actually use.	What you paid for. On laptops with integrated graphics, expect a slice to be reserved — that is normal, and it should be a small slice.

The commonest silent downgrade

A prebuilt or a laptop advertised with 16 GB, delivered as one 16 GB stick. It is technically the advertised capacity and it is meaningfully slower than two 8 GB sticks, because it halves the memory bandwidth. Check the channel count, not the total, and factor the price of a second stick in.

Walk away if

A single error in any memory test at stock or rated settings.
Memory that will not post at its own rated profile.
Mismatched sticks sold as a matched kit, where stability was never tested.
Bandwidth around half of expected, on a machine sold as dual channel.

Step six

Storage

The headline sequential number sells drives; the small random number is what you feel every day. And the number nobody quotes — sustained write, after the cache runs out — is where cheap drives fall apart.

20 minutesTest every driveSMART matters more than speed

Get these first

CrystalDiskMarkFreeWindowsSequential and random drive speed. The numbers every SSD listing quotes.CrystalDiskInfoFreeWindowsSMART data: drive health, power-on hours, total bytes written, link speed.HD TuneFree tierWindowsFull-surface read scan for hard drives. Draws the dips where a platter is going.DiskSpdFreeWindowsMicrosoft’s scriptable storage tester, for when you need the exact same run twice.Blackmagic Disk Speed TestFreemacOSOne-button sustained read/write on a Mac, internal or external.

Four tests per drive

SMART first, always, from step 02. A fast dying drive is still a dying drive.
CrystalDiskMark on default settings. Read the sequential row for bulk transfers, and the RND4K Q1T1 row for how the machine will feel. That last one is the number that decides whether the computer feels quick.
Test the sustained write. Copy a 100 GB folder onto the drive and watch the transfer speed. Consumer SSDs write fast into a small fast cache and then fall to their real speed. A good drive settles somewhere respectable; a cheap DRAM-less QLC drive can collapse to under 150 MB/s and stay there.
Check the link speed in CrystalDiskInfo. A Gen4 drive negotiated at Gen3 x2 is in a slot that shares lanes with something else, and it is losing most of its performance to a motherboard layout rather than a fault.
Hard drives get a full surface scan. HD Tune’s read benchmark draws a line across the whole platter; dips and spikes in that line are the drive struggling to read areas it will soon fail to read at all. It takes hours on a large drive and it is worth every minute.
Listen to a hard drive. Clicking, grinding or a repeated seek-and-reset is a drive with weeks left, whatever SMART says.

Storage numbers, in order of how much they matter

Metric	Which way	What it tells you	Healthy looks like
RND4K Q1T1 read / write	Higher is better	Small scattered operations at a single queue depth — how the OS and applications really behave.	The most important row in the whole result. A good NVMe manages tens of MB/s read and rather more on write; a hard drive manages around 1 MB/s, which is why they feel the way they do.
Sequential read / write (SEQ1M)	Higher is better	Big continuous files. The number on the box.	Close to the rated figure for the model. Well under it usually means the wrong PCIe link, a full drive, or heat.
Sustained write after the cache	Higher is better	What the drive really does once the fast cache is exhausted.	Holds a sensible fraction of its rated write. A collapse to double digits means QLC flash with no DRAM, which is fine for storage and painful as a system drive.
Negotiated link speed	Must match the spec	The PCIe generation and lane count actually in use.	The same as the drive supports, assuming the board does too. Gen4 x4 for a Gen4 drive in a proper slot.
Drive temperature under sustained write	Lower is better	NVMe drives throttle hard when hot.	Under about 70°C under load, and under 50°C at idle. A drive that idles hot has no airflow or no heatsink.
Free space at test time	Higher is better	Not a result, but it changes every result above.	At least 20% free. A nearly full SSD benchmarks badly and lives badly — do not judge a drive that is at 97%.
HD Tune read curve (hard drives)	Must match the spec	Read speed across the whole platter surface.	A smooth curve that falls gently from outer to inner tracks. Dips, spikes or a sawtooth mean a surface going bad.

Why your fast drive benchmarks slow

Before you blame the drive: it may be over 80% full, it may be the drive Windows is currently indexing, it may be behind a chipset-connected slot rather than the CPU one, or it may simply be hot. Free some space, wait for indexing, check the slot, then re-test. Storage results are the easiest of all to get wrong.

Walk away if

Any reallocated or pending sectors.
A hard drive that clicks, grinds or resets.
Health below 90% on a drive that forms part of the asking price.
Sustained write collapsing to double digits on a drive sold as a system drive.
A drive that disappears from the system mid-test and reappears on reboot.

Step seven

Heat, noise and power

Heat is what turns a good score into a bad computer. Everything here is about what happens in minute ten, not minute one — and about the one number that lets you compare your machine to a stranger’s.

45 minutesAmbient temperature requiredDelta is the number that travels

Get these first

HWiNFO64FreeWindowsEvery sensor on the machine, plus CSV logging. The one tool to install first.OCCTFree tierWindowsPower, 3D, VRAM and memory tests that detect calculation errors, not just crashes.Prime95FreeWin / Mac / LinuxSmall FFT torture test — worst-case heat, for proving a cooler rather than scoring a chip.FurMark 2FreeWindowsAbsolute worst-case GPU power and heat. Useful in short bursts, not a performance test.

The soak

Write down the room temperature. Nothing below means anything without it.
Cinebench on a 10-minute loop with HWiNFO logging. Record peak and settled temperature, peak and settled clock, and package power at both points.
OCCT’s combined power test for 15 minutes. This loads the processor and graphics card at once, which is the condition that finds a tired power supply. A machine that survives each test alone and reboots under both together has a power delivery problem, not a CPU problem.
Work out the delta. Component temperature minus room temperature. That figure is comparable between houses, seasons and countries in a way a raw temperature never is, and it is the only honest way to compare your cooling to someone else’s.
Listen, at 30 centimetres, under load. A phone decibel app is not laboratory equipment, but it is perfectly good for comparing before and after, or idle against load. What you are really listening for is character: bearing rattle, coil whine, pump gurgle, a fan catching a cable.
Measure at the wall with a plug-in power meter if you have one. It checks the power supply is not being asked for more than it has, and it tells you what the machine will cost to run.
FurMark, briefly, if at all. It produces more heat than any real workload and is useful as a worst-case ceiling. It is not a performance test and it is not a stability test — do not leave it running for an hour to prove something.

Thermal and power readings

Metric	Which way	What it tells you	Healthy looks like
CPU delta over ambient, settled	Lower is better	Core temperature minus room temperature after ten minutes of full load.	Compare against the same cooler and chip elsewhere. This is the number to quote and the number to ask for — a raw temperature without an ambient is unusable.
GPU delta over ambient, settled	Lower is better	The same measurement for the graphics card.	Steady after ten minutes, not still climbing. A card still warming at minute fifteen has a cooling problem you will meet later.
Temperature at minute 10 vs minute 1	Lower is better	Whether the cooling reaches equilibrium at all.	Flat. A line that is still rising when the test ends means the cooler is losing.
Clock held at minute 10	Higher is better	The performance that actually survives the heat.	Close to the clock at minute one. This is the single most useful thermal measurement there is.
12V rail under combined load	Must match the spec	Whether the power supply holds its voltage when everything pulls at once.	Within about 5% — roughly 11.4 to 12.6 V. Board sensors are rough, so look for a large sag rather than a small one.
Shutdowns or reboots under combined load	Must be zero	The clearest power supply test there is.	None. An instant reboot when a combined test starts is a power supply that cannot do its job any more.
Noise under load, at 30 cm	Lower is better	What you will actually live with.	Consistent and smooth. Character matters more than volume — a rattle at 38 dB is worse to own than a whoosh at 45.
Power at the wall, gaming	Must match the spec	Real system draw.	Sensibly below the power supply rating, with headroom for spikes. A system pulling near its supply rating will trip under transient loads.

Used power supplies

This is the one part where the honest answer is usually do not. The capacitors age whether the unit is used or not, a failure can take other parts with it, and it is the cheapest component to replace with a new one that carries a warranty. If you are buying a whole machine that includes one, at least find out how old it is, whether any warranty remains, and run a combined load test before you accept it.

Walk away if

A reboot or shutdown the moment a combined CPU and GPU load starts.
Temperature still climbing after fifteen minutes of steady load.
A clock speed that has dropped by a quarter or more by minute ten.
Grinding, rattling or a pump that gurgles constantly rather than briefly.
A burning or hot-plastic smell under load, at any temperature reading.

Step eight

Real world: the only benchmark that pays rent

Average frame rate is the number in the advert. The 1% low is the number you feel. Two machines can post the same average and one of them is smooth while the other stutters — and the gap between those two numbers is where the truth is.

40 minutesYour games, your settingsLows matter more than average

Get these first

CapFrameXFreeWindowsCaptures frametimes in any game and reports average, 1% low and 0.1% low. The important one.Intel PresentMonFreeWindowsThe capture engine underneath most FPS tools, with its own overlay and GPU-busy metric.MSI Afterburner + RTSSFreeWindowsThe on-screen overlay: clocks, temps, power and frametimes while you actually play.PugetBenchFree tierWin / MacScores Premiere, After Effects, Photoshop and Resolve using the real applications.Blender BenchmarkFreeWin / Mac / LinuxReal render workload for CPU and GPU, with a public results database to compare against.HandBrakeFreeWin / Mac / LinuxTranscode a clip you supply. A real, repeatable job rather than a synthetic score.PCMark 10Free tierWindowsWhole-system score built from office, browsing and content-creation workloads.

Capturing something that means something

Install CapFrameX (or Intel PresentMon, which is the capture engine underneath most of these tools). It records the time each individual frame took, which is what the eye is actually responding to.
Set up an overlay with Afterburner and RTSS so you can watch frame rate, frametime, clocks, temperatures and VRAM usage while you play, not afterwards.
Pick three games you genuinely play, at your real resolution and your real settings. A benchmark at settings you will never use tells you about a machine you do not own.
Launch each game once and exit before you measure. The first launch compiles shaders and will wreck your numbers if you record it.
Capture 60 to 90 seconds of the same section, three times. Use a built-in benchmark where one exists — it repeats exactly, which manual play never does.
Read the frametime graph, not just the numbers. A flat line is a smooth game. Regular spikes are stutter with a cause worth chasing — shader compilation, a background task, VRAM overflowing, a drive that cannot keep up with streaming.
Then test the actual job, if this machine is for work: a real export in Premiere or Resolve, a Blender render, a Handbrake transcode, a full compile. PugetBench scores the real applications rather than approximations of them.

Frame metrics, and what each one is telling you

Metric	Which way	What it tells you	Healthy looks like
Average FPS	Higher is better	Total frames divided by time. The headline, and the least useful of the three.	In line with published reviews at the same settings and resolution. Use it to check the machine is in the right ballpark, then stop looking at it.
1% low FPS	Higher is better	The average of the slowest one percent of frames. This is what “smooth” means.	Roughly two thirds of the average or better. If it is below half the average, something is wrong and it is worth finding.
0.1% low FPS	Higher is better	The worst hitches — the ones you notice as a jolt rather than as slowness.	Not catastrophically below the 1% low. A cliff here is stutter with a specific cause, not a slow machine.
Frametime variance	Lower is better	How much the millisecond cost of each frame jumps about.	Low and even. A locked 16.6 ms feels better than a jittery 12 ms, which is why variance matters more than speed.
GPU utilisation while gaming	Higher is better	Whether the graphics card is the thing doing the limiting.	95 to 100% in a GPU-bound game. Consistently lower means the processor, the memory or a frame cap is holding it back.
VRAM used vs available	Lower is better	Whether textures are overflowing into system memory.	Comfortably under the card capacity. Overflow shows up as a collapsing 1% low with a healthy average — a very distinctive signature.
Blender samples per minute	Higher is better	Real render throughput, with a public results database to compare against.	In line with the same hardware on Blender Open Data.
Export or compile time	Lower is better	The one benchmark your working day actually cares about.	Whatever beats your current machine by enough to justify the money.

What the gap is telling you

A healthy machine has an average and a 1% low that sit reasonably close together. A big gap between them almost always has a specific, findable cause: shader compilation on first run, video memory overflowing, a background process, thermal throttling arriving after a few minutes, a slow drive streaming assets, or a processor that cannot feed the graphics card. Chase the gap, not the average.

Walk away if

1% low under half the average in a game that reviews say runs smoothly.
Frame rate falling steadily over ten minutes of play — that is heat.
Regular hitches with the graphics card sitting well below full utilisation.
Any crash to desktop, driver reset or black screen during normal play.

Part 2

Everything else you might be buying

The eight steps cover a desktop. Monitors, laptops, peripherals, consoles and Macs each have their own faults and their own tests — most of them faster than the ones above.

Category

Monitors

A panel cannot be benchmarked the way a chip can, but it can be inspected exhaustively in ten minutes with a browser and a dark room. Nearly every fault is visible if you know which pattern to put on screen.

10 minutesBrowser onlyDo it in a dark room

Get these first

TestUFOFreeWebConfirms the real refresh rate and makes ghosting, overshoot and frame skipping visible.Lagom LCD testFreeWebThe reference set of display test patterns: black level, gamma, banding, uniformity.Dead Pixel TestFreeWebFull-screen solid colours for finding dead and stuck pixels in under a minute.EIZO Monitor TestFreeWebA guided run through every panel test in one place. Good when you are in a hurry.RtingsFreeWebMeasured display data — response times, VRR range, real contrast — not marketing numbers.

The panel pass

Full-screen solid colours first. White, black, red, green, blue and grey. Dead pixels show on white, stuck sub-pixels show on the colours. Do this at native resolution with the browser in full screen.
Backlight bleed, lights off, black screen, brightness at about half. Then move your head. Glow that shifts as you move is IPS glow and is normal for the technology. Patches that stay exactly where they are, usually at the corners, are bleed and are a defect.
Uniformity on a mid-grey field. Look for tinting and brightness banding across the panel. Repeat at a couple of brightness levels; some panels are only bad at one.
Confirm the refresh rate is real. TestUFO reports what the browser is actually receiving. A monitor sold as 165 Hz that is running at 60 usually just needs setting properly — but sometimes it is the cable, and sometimes the claim was never true.
Motion: ghosting, overshoot, frame skipping. The moving-object tests make all three obvious. Trails behind objects are slow pixels; bright halos in front of them are the overdrive set too aggressively.
Test variable refresh rate properly by running something with a swinging frame rate. VRR flicker on some panels shows up as brightness pulsing in dark scenes, and it is the fault most likely to be missed at a meet-up.
OLED: hunt for burn-in. Full-screen grey at moderate brightness. Look for ghosts of a taskbar, a game HUD or a browser chrome. Then check the panel’s own usage hours in its service menu if it has one.
Every input, and the stand. Each HDMI and DisplayPort, the USB hub if fitted, the speakers, the buttons, the tilt and height mechanism, and whether the VESA mount holes are intact.

Display checks

Metric	Which way	What it tells you	Healthy looks like
Dead and stuck pixels	Must be zero	Pixels that no longer change, or are frozen on one colour.	Zero on a monitor sold as perfect. Manufacturers tolerate a few under warranty; a private seller does not get that allowance unless the price reflects it.
Backlight bleed	Lower is better	Light escaping around the edges of a black screen.	Minimal, and invisible at normal room lighting. Some is inherent to LCD; large corner patches are not.
Verified refresh rate	Must match the spec	The rate the display is genuinely running at.	The advertised maximum, over the cable you will use, at the resolution you will use.
Overshoot / inverse ghosting	Lower is better	Bright halos ahead of moving objects from overly aggressive overdrive.	None visible at the recommended overdrive setting. If only the lowest setting is clean, the panel is worse than its rating.
Frame skipping	Must be zero	Frames dropped at the top refresh rate, often over a marginal cable.	None. If skipping appears at the maximum rate, try the supplied cable and a different port before blaming the panel.
OLED burn-in	Must be zero	Permanent ghosting of static elements.	None on a uniform grey field. Any visible ghost is permanent and only gets worse.
Panel usage hours	Lower is better	How much life the backlight or emitter has already used.	Available in the service menu on many models. Worth asking for, and worth a discount if it is high.

Walk away if

Burn-in on an OLED, at any severity.
Dead pixels the seller did not disclose.
Cracked or peeling anti-glare coating — it cannot be repaired.
Frame skipping that survives a cable and port change.
Flickering at any refresh rate, or a backlight that takes seconds to come on.

Category

Laptops

Everything from the eight steps applies, plus three things that do not exist on a desktop: a battery that has been quietly dying since the day it was made, a power limit that changes depending on what the machine is plugged into, and a chassis that has been carried around for years.

30 minutesTest plugged in AND on batteryBattery is the hidden price

Get these first

HWiNFO64FreeWindowsEvery sensor on the machine, plus CSV logging. The one tool to install first.ThrottleStopFreeWindowsShows exactly why an Intel laptop is slowing down, and lets you undervolt it.AMD Ryzen MasterFreeWindowsPer-core clocks, temperature and power limits on Ryzen, plus Curve Optimizer.BatteryInfoViewFreeWindowsLive battery wear and charge/discharge rate without generating a report.Cinebench 2026FreeWin / MacThe standard sustained CPU render test, single and multi-core, with a timed loop mode.

What is different about a laptop

Battery report, first thing. Open a terminal and run powercfg /batteryreport. It writes an HTML file and tells you where. Read the design capacity against the full charge capacity, and read the cycle count. This is a number you cannot argue with and it is worth real money.
Run the same benchmark twice: on mains, then on battery. Many machines halve their power limit when unplugged. If you intend to work unplugged, the battery figure is the only one that matters to you.
Run a 10-minute sustained load and watch the throttle reasons in HWiNFO or ThrottleStop. Thin laptops throttle by design; what you are looking for is whether it settles at a sensible level or collapses.
Check every power profile. Most laptops ship with quiet, balanced and performance modes that change results by tens of percent. Test the one you will actually use, and note which one you tested.
Feel the chassis and the hinge. Flex, creaks, a hinge that has started to lift the lid’s bottom edge, or a base plate bowing outwards — that last one is a swollen battery and it is a fire risk, not a cosmetic issue.
Every key, the trackpad, every port. Plug something into each USB port, test the card reader, the headphone jack, the webcam and the microphone, and charge over each port that claims to charge.
Listen to the fans and check the vents. A laptop that has lived on a duvet has a heatsink packed with dust and a fan bearing on its way out.
Check the warranty by serial number on the manufacturer’s site while you are still there, and check that nothing is locked to the previous owner — BIOS password, BitLocker, or a corporate management enrolment.

Laptop-specific numbers

Metric	Which way	What it tells you	Healthy looks like
Full charge vs design capacity	Higher is better	How much battery is left, as a percentage of new.	Above 85% is healthy. 80 to 85% is fair wear. Under 80% means a replacement, so subtract that cost from the offer.
Cycle count	Lower is better	How many full charges the battery has been through.	Under 500 on most machines is comfortable. Read it alongside capacity, not instead of it.
Sustained score, plugged in	Higher is better	What the machine does with all the power it is allowed.	In line with reviews of the same model. Notebook results vary far more between chassis than between chips.
Sustained score, on battery	Higher is better	What it does unplugged, which is often a very different machine.	Whatever you can live with. A 40 to 60% drop is common and is not a fault — it is a specification nobody advertises.
Sustained package power	Higher is better	The wattage the chassis can actually keep fed and cooled.	Near the model published figure. Well below it means dust, dried paste, or a machine set to a quiet profile.
Skin temperature at the keyboard	Lower is better	What your hands will experience.	Uncomfortable is normal under full load. Untouchable is a cooling system that needs servicing.
Chassis and hinge condition	Must match the spec	The part no benchmark reports.	Flat base, tight hinge, no creaking. A bowed base plate is a swollen battery — stop and do not buy it.

Walk away if

A base plate that bows, or a trackpad that has lifted. That is a swollen battery.
A BIOS password, BitLocker lock, or corporate enrolment nobody can remove.
Liquid damage indicators tripped, or corrosion visible in a port.
A hinge that has begun to pull its mounts out of the lid.
Sustained performance a long way below reviews of the same model, with no dust and no fix offered.

Category

Keyboards, mice and headsets

Small money, fast tests, and the faults are binary: a key either registers or it does not, a switch either double-clicks or it does not. All of this runs in a phone browser at the meet-up.

5 minutesBrowser onlyNo excuse for skipping it

Get these first

Keyboard CheckerFreeWebShows every key registering. Finds dead keys and chatter on a phone at the meet-up.Key-TestFreeWebSecond opinion on key registration, and it shows rollover when you mash keys.Mouse Rate CheckerFreeWebMeasures actual polling rate, plus buttons, scroll and double-click faults.

Keyboards

Press every single key in a key-test page and watch them all light up. Include the function row, the number pad, the modifiers and anything the layout hides behind a function layer.
Test for chatter. Type a long repeated string. A switch that has started to fail produces doubled characters — one press, two letters — and it only shows up on a fast run.
Check rollover. Hold down six or more keys at once and see how many register. Anti-ghosting is a specification people claim and boards do not always have.
Confirm the polling rate if it was part of the sale. It is a property of the controller, not the switches, and it is regularly overstated.
Feel the stabilised keys — space, enter, shift, backspace. Rattle and bind are fixable but they are work, and they are worth money off.
Check the cable and the connector, and on a wireless board, the battery and the dongle. A missing proprietary dongle can make a board worthless.

Mice

Every button, several times each, including the side buttons and the wheel click.
Test for double-clicking deliberately: single-click slowly, thirty times, and watch for a double registering. This is the most common failure in used mice and it is the switch wearing out.
Scroll wheel, both directions, slowly. Skipping and phantom reverse scroll are an encoder going bad.
Move the sensor across the surface you will use — glass, cloth, wood — and watch for jitter, stutter or a cursor that jumps.
Check polling rate against what was advertised, then check the cable at the strain relief and the feet for wear.
Wireless: check the battery the same way you would a laptop, and confirm the receiver is included.

Peripheral checks

Metric	Which way	What it tells you	Healthy looks like
Dead or chattering keys	Must be zero	Keys that do not register, or register twice.	Zero. On a hot-swappable board a single bad switch is a two-pound fix; on a soldered one it is a soldering iron.
Mouse double-click on a single press	Must be zero	A worn switch registering twice.	Never. If it happens once in thirty presses, it will happen constantly within months.
Polling rate	Must match the spec	How often the device reports to the computer.	The advertised figure. 1000 Hz is the normal maximum unless the device specifically supports more.
Key rollover	Higher is better	How many simultaneous keys register.	Whatever was claimed. Full N-key rollover means every key at once, and plenty of boards claiming it do not have it.
Sensor jitter	Must be zero	Cursor movement the hand did not make.	None on the surface you will actually use.
Battery health, wireless	Higher is better	Runtime against the original claim.	Ask for the real figure, not the box figure. Peripheral batteries are rarely replaceable.

Category

Consoles

Fixed hardware, so there is nothing to benchmark and everything to inspect. The value is in the condition, the account state and the twenty minutes you spend making it hot.

30 minutesMostly inspectionMake it hot before you pay

The console pass

Match the serial number on the underside label against the one in the system information menu. A mismatch means a replaced shell or a replaced board.
Check the warranty and whether it transfers. Consoles are usually still young enough for this to matter.
Confirm the previous owner is gone. Their account deactivated, the console deregistered as their primary, and a factory reset agreed. A console still tied to someone else’s account is a support ticket you will lose.
Run a demanding game for at least twenty minutes. This is the whole test. Thermal faults, dust-packed heatsinks and dying fans all need heat and time.
Listen. A brief spin-up is normal. A constant jet-engine roar, a rattle or a grinding note means the fan or the heatsink needs attention.
Test the disc drive if it has one: eject, load, read, and play from disc for a few minutes. Drives are the commonest hardware failure and among the most expensive to fix.
Test every controller for stick drift — put it down, hands off, and watch whether anything moves on screen. Then every button, both triggers, rumble and the charge port.
Every port on the console, plus the HDMI at the resolution and refresh rate you intend to use, and the storage: check free space and whether an expansion card is included.

Console checks

Metric	Which way	What it tells you	Healthy looks like
Serial on label vs in software	Must match the spec	Whether the shell and the board belong to each other.	Identical. A mismatch is a repair, a swap, or something worse.
Account and activation state	Must match the spec	Whether it is really yours after you pay.	Fully deactivated and factory reset, done in front of you.
Fan noise after 20 minutes of load	Lower is better	The cooling system, and how much dust is in it.	Loud but steady is fine. Rattling, grinding or a rising whine is not.
Thermal shutdowns or warnings	Must be zero	Whether it can sustain a full load at all.	None. A console that warns or shuts down after ten minutes has a problem that always gets worse.
Controller stick drift	Must be zero	Input with nobody touching it.	None on any stick. Drift is a repair, and on some controllers it is a replacement.
Disc drive read	Must match the spec	Eject, load and sustained read from a physical disc.	Smooth and quiet, first time. Grinding or repeated retries means a failing laser or a worn mechanism.

Category

Macs

Different tools, same logic — with one extra step that has nothing to do with performance and can make the whole machine worthless: the activation lock.

20 minutesCheck the lock FIRSTBattery is the usual cost

Get these first

Geekbench 6Free tierEverythingShort mixed-workload CPU score. The only benchmark that compares a phone, a Mac and a PC.Cinebench 2026FreeWin / MacThe standard sustained CPU render test, single and multi-core, with a timed loop mode.coconutBatteryFree tiermacOSMac and iPhone battery health, cycle count and manufacture date.Blackmagic Disk Speed TestFreemacOSOne-button sustained read/write on a Mac, internal or external.smartmontoolsFreeWin / Mac / LinuxThe same SMART data from a terminal, on machines CrystalDiskInfo will not run on.

The Mac pass

Activation Lock, before anything else. Confirm Find My is switched off and the machine has been signed out of the seller’s Apple Account, in front of you. A locked Mac cannot be reset, cannot be resold and cannot be unlocked without the original owner. Nothing else on this list matters if this one fails.
Check coverage by serial number on Apple’s own site, and confirm the serial matches the one in About This Mac.
coconutBattery for battery health, cycle count and the manufacture date — which also tells you whether the machine really is the year it was sold as.
Geekbench and Cinebench for single and multi-core, both of which have deep Apple Silicon comparison pools.
Watch for sustained throttling on fanless machines. An Air will slow down under a long load by design; the question is where it settles.
Blackmagic Disk Speed Test for the internal drive, and check the SMART status. Base-storage models with soldered drives have a real, finite write life.
Run Apple Diagnostics and note any reference codes. Then check the display for staingate or delamination, the keyboard for dead keys, and every port.

Mac-specific checks

Metric	Which way	What it tells you	Healthy looks like
Activation Lock / Find My	Must be zero	Whether the machine is still tied to the seller.	Off, verified in front of you before money moves. There is no workaround later.
Battery cycle count and health	Higher is better	The commonest wear item on any Mac laptop.	Above 85% health. Apple treats 1,000 cycles as the design life on recent machines.
Sustained multi-core score	Higher is better	What it holds under a long load, not the burst.	In line with the same model. Fanless machines settle lower and that is expected.
Drive write total	Lower is better	How much of a soldered, unreplaceable SSD has been used.	Modest. On a base-storage machine that has swapped heavily for years, this is a genuine concern.
Apple Diagnostics result	Must be zero	Reference codes for detected hardware faults.	No codes. Any code is worth looking up before you agree a price.

Part 3

What the numbers mean

You have a folder of scores. On their own they are trivia. This part turns them into a decision, and then into a price.

Interpretation

Reading the results

A score is only ever a comparison, so the skill is knowing what to compare against and how much difference is allowed to be nothing.

The part most guides skipUse several sourcesMedian, not maximum

Where the baseline lives

3DMark result searchFreeWebFilter millions of submitted runs by exact GPU and CPU to find your expected score.TechPowerUp GPU databaseFreeWebEvery card ever made: real specs, memory type, TDP, and which die is actually inside.GPU hierarchyFreeWebOne ranked ladder of graphics cards by measured game performance, kept current.CPU hierarchyFreeWebThe same ladder for processors, split into gaming and productivity.PassMark CPUFreeWebEnormous sample sizes and per-model score distributions. Good for spotting an outlier.PassMark GPUFreeWebThe graphics-card half of the same database.Gamers NexusFreeWebReviews with published methodology and error bars. Use their charts as your target.HWBOTFreeWebOverclocker submissions. Useful for seeing what a part does at its ceiling.r/buildapcFreeWebPost your numbers with your full spec and someone will tell you what is wrong.r/hardwareFreeWebWhere the methodology arguments happen. Read before trusting any single review.

How to find your expected score

Search the benchmark’s own result database for your exact model. 3DMark’s search lets you filter by graphics card and processor together, which matters — the same card in two different systems posts different overall scores.
Take the median, not the top. Leaderboards are overclockers on exotic cooling. You are trying to find out whether your example is normal, not whether it is a record.
Cross-check against a review that publishes its methodology, so you know what settings produced the number you are comparing against.
For laptops, compare against the same model, not the same chip. Chassis design changes sustained performance more than silicon does.
If you cannot find a baseline, make one: run the same benchmark on a machine you already trust, and compare relative rather than absolute.

Gap to the median	What it means	What to do
Within 3%	Noise. This is run-to-run variance, not a difference.	Nothing. Stop measuring and go and use the machine.
3 to 7% down	Normal spread. Silicon quality, board power settings, memory speed, ambient temperature.	Check XMP is on and the cooling is clean, then accept it.
7 to 15% down	Something specific is wrong, and it is usually configuration rather than hardware.	Work through the list below. Most of these are free to fix and worth fixing before you accept the price.
More than 15% down	A fault, a fake, a wrong part, or a machine being throttled hard.	Do not pay for it until you know which. Go back to step 01.
Above the median	Usually good cooling or a mild overclock. Occasionally a benchmark that was not run properly.	Check nothing is overclocked, and re-run at stock. You want to buy the part, not somebody’s tuning.

When a number is low, this is usually why

Multi-core score low, single-core fine: Thermal or power limit. Check the settled clock, then the cooler mount, then the power settings in BIOS.
Both processor scores low, temperatures fine: A power limit set deliberately, a quiet profile, or Windows on a power-saving plan. Check before you blame the chip.
Graphics score low, temperatures fine: Driver state, the card in the wrong slot, Resizable BAR off, or the display plugged into the motherboard instead of the card.
Everything a bit low, across the board: Memory running at its default speed because XMP or EXPO was never enabled. Costs 5 to 15% and takes one BIOS setting to fix.
Fine at first, worse over ten minutes: Heat. Dust, dried paste, a bad mount, or a cooler that was never adequate.
Average frame rate fine, 1% low terrible: Video memory overflowing, a slow drive streaming assets, shader compilation, or a background process. Watch VRAM usage and the frametime graph together.
Storage far below rated: Wrong PCIe slot, a nearly full drive, thermal throttling, or a cheap drive whose cache has run out.
Results that change every run: Something is still running. Reboot, close everything, let the machine cool, and start again.

One site to avoid

UserBenchmark still ranks highly in search results and is still not usable for this. Its scoring weights and its editorial commentary have made it untrusted enough that the major hardware communities on Reddit ban links to it outright. Use the result databases above, or a review that publishes how it tested.

The honest comparison

The most useful baseline is not a stranger’s. It is your own, from six months ago, on the same machine, with the same settings. Save your results. A machine that has lost 12% against itself is telling you something no leaderboard can.

Decision

Red flags, ranked

Roughly in order of how quickly you should stop. The first four are not negotiations — they are the end of the conversation.

The seller will not let you test it. Nothing else on this page matters. An honest seller with a working machine has no reason to refuse ten minutes.
It is not the part it claims to be. A flagged card, a mismatched serial, a laptop chip sold as desktop, half the advertised memory. This is fraud, not a fault.
A locked device. Activation Lock, a BIOS password, corporate enrolment, an account nobody can sign out of. You are buying a paperweight.
A swollen battery. A bowed base, a lifted trackpad, a case that will not close flat. That is a fire risk being carried into your house.
Artifacts, or any memory error. Graphics or system memory, at stock settings, in any test. There is no acceptable amount and it does not improve.
Reallocated or pending sectors. The drive has already begun to fail and it will not stop.
A reboot under combined load. The power supply cannot do its job, and a failing supply can take other parts with it.
Burnt, melted or browned power connectors. Especially the 12VHPWR plug on recent high-end cards.
Corrosion, liquid damage indicators, or a burnt smell. Liquid damage is progressive; it is fine right up until it is not.
Bulging capacitors, or a cracked PCIe slot. Board-level damage that will outlive your patience.
Heavy smoke residue. Corrosive, conductive, and impossible to get out of a heatsink.
A story that keeps changing. How old it is, why it is for sale, what has been replaced. The inconsistency is the information.

And the softer ones

Stock photos rather than photographs of the actual unit, and a refusal to send one with today’s date on a note next to it.
Pressure to pay a deposit to “hold” it.
A price meaningfully below every other listing for the same thing, with an urgent reason attached.
A seller who moves the conversation off-platform immediately, or who will only meet somewhere you cannot plug the machine in.

Money

Turning a number into a price

A shortfall you can name is a discount you can ask for. Bring the evidence, name the fix, name the cost, and let the number do the arguing.

Most sellers are not trying to cheat anybody — they genuinely do not know their thermal paste is five years old or that their memory was never running at its rated speed. That makes this a much easier conversation than people expect, as long as you arrive with a measurement rather than an opinion. “It feels slow” gets you nowhere. “It scores 14% under median and throttles at minute three, here is the log” gets you a discount or a repaste.

What you found	What it actually costs	What to ask for
Battery under 80%	A replacement battery plus fitting.	The full replacement cost off. It is a consumable and it is measurable.
Hotspot delta over 25°C	Paste, pads and an afternoon, or a shop bill.	The service cost off, or ask them to do it before handover.
Single-channel memory	A matching stick, and 10 to 20% of the performance until you fit it.	The price of the missing stick.
SSD past half its rated writes	A shortened remaining life on a part you will replace sooner.	A proportion of a replacement drive, scaled to how much is gone.
No warranty left	All of the risk moves to you at the moment of handover.	Meaningfully less than an otherwise identical unit with cover remaining.
No box, cables or accessories	Replacements, and a lower price when you come to resell it.	Replacement cost, plus a little for the resale hit.
Fans rattling or grinding	Replacement fans, which on a graphics card can mean a specific part.	The part cost. Check the part exists before you agree.
Score 10 to 15% under median, cause found	Whatever the fix costs, once you know what it is.	The fix, or the discount. Not both, and not nothing.
Cosmetic damage only	Nothing functional. It costs you at resale, not in use.	A modest reduction. Do not oversell this one — it weakens the real points.

How to actually say it

Show the screen, not the conclusion. “Here is the log — it starts at 5.1 GHz and finishes at 3.9, and the hotspot delta is 31 degrees. That is a repaste, which is about this much. Would you take that off, or would you rather do it before I collect?” That is a solvable problem with two acceptable answers, which is what makes it work.

If you are the seller

Every row above is also a list of things you can fix in an afternoon to protect your own price. A repaste, a second stick of memory, a clean install and a box of the right cables will earn back more than they cost, and posting your benchmark scores in the listing removes the buyer’s main reason to haggle.

Part 4

Take it with you

The part you will actually use. Ticks are saved in your browser, so you can start a list at home and finish it standing in somebody’s kitchen.

Reference

Every tool on this page

All of it, grouped, with a link each. Almost everything here is free; where it is not, the free tier or the trial is enough to answer the question you are asking.

Identity & health07

HWiNFO64FreeWindowsEvery sensor on the machine, plus CSV logging. The one tool to install first.
CPU-ZFreeWindowsExact CPU model and stepping, and the memory tab that exposes channel count and timings.
GPU-ZFreeWindowsGraphics card identity, VBIOS, PCIe link width, and a counterfeit-card check.
CrystalDiskInfoFreeWindowsSMART data: drive health, power-on hours, total bytes written, link speed.
smartmontoolsFreeWin / Mac / LinuxThe same SMART data from a terminal, on machines CrystalDiskInfo will not run on.
coconutBatteryFree tiermacOSMac and iPhone battery health, cycle count and manufacture date.
BatteryInfoViewFreeWindowsLive battery wear and charge/discharge rate without generating a report.

Processor07

Cinebench 2026FreeWin / MacThe standard sustained CPU render test, single and multi-core, with a timed loop mode.
Geekbench 6Free tierEverythingShort mixed-workload CPU score. The only benchmark that compares a phone, a Mac and a PC.
7-Zip benchmarkFreeWindowsBuilt into 7-Zip (Tools › Benchmark). Runs offline, in 60 seconds, on a stranger’s PC.
y-cruncherFreeWin / LinuxPi calculation. Doubles as the harshest realistic CPU and memory stability test there is.
Prime95FreeWin / Mac / LinuxSmall FFT torture test — worst-case heat, for proving a cooler rather than scoring a chip.
Blender BenchmarkFreeWin / Mac / LinuxReal render workload for CPU and GPU, with a public results database to compare against.
HandBrakeFreeWin / Mac / LinuxTranscode a clip you supply. A real, repeatable job rather than a synthetic score.

Graphics07

3DMarkFree tierWindowsThe GPU benchmark with the largest comparison database. Free tier covers Time Spy and Steel Nomad.
Unigine SuperpositionFree tierWin / LinuxRepeatable GPU score plus a looping stress mode that makes artifacts obvious on screen.
Unigine HeavenFreeWin / LinuxAncient, tiny, and still the fastest way to smoke-test a very old card on someone’s desk.
OCCTFree tierWindowsPower, 3D, VRAM and memory tests that detect calculation errors, not just crashes.
MSI KombustorFreeWindowsLoops a 3D scene with automatic artifact detection — the dying-VRAM test.
FurMark 2FreeWindowsAbsolute worst-case GPU power and heat. Useful in short bursts, not a performance test.
memtest_vulkanFreeWin / LinuxTests video memory for errors specifically. Catches bad VRAM that games only stutter on.

Memory05

AIDA64 ExtremeTrialWindowsThe memory bandwidth and latency benchmark everyone quotes. Trial period is enough.
MemTest86Free tierBootable USBTests RAM outside the OS, so nothing is in the way. The one to run overnight.
TestMem5FreeWindowsFinds memory errors fast — usually inside an hour with the right config.
Karhu RAMTestPaidWindowsThe gold standard for coverage-based memory testing. Worth it if you tune RAM often.
HCI MemTestFree tierWindowsOld, ugly, and still trusted. Free version runs one instance per thread.

Storage04

CrystalDiskMarkFreeWindowsSequential and random drive speed. The numbers every SSD listing quotes.
HD TuneFree tierWindowsFull-surface read scan for hard drives. Draws the dips where a platter is going.
DiskSpdFreeWindowsMicrosoft’s scriptable storage tester, for when you need the exact same run twice.
Blackmagic Disk Speed TestFreemacOSOne-button sustained read/write on a Mac, internal or external.

Real-world & frametimes05

CapFrameXFreeWindowsCaptures frametimes in any game and reports average, 1% low and 0.1% low. The important one.
Intel PresentMonFreeWindowsThe capture engine underneath most FPS tools, with its own overlay and GPU-busy metric.
MSI Afterburner + RTSSFreeWindowsThe on-screen overlay: clocks, temps, power and frametimes while you actually play.
PCMark 10Free tierWindowsWhole-system score built from office, browsing and content-creation workloads.
PugetBenchFree tierWin / MacScores Premiere, After Effects, Photoshop and Resolve using the real applications.

Displays & peripherals07

Lagom LCD testFreeWebThe reference set of display test patterns: black level, gamma, banding, uniformity.
TestUFOFreeWebConfirms the real refresh rate and makes ghosting, overshoot and frame skipping visible.
Dead Pixel TestFreeWebFull-screen solid colours for finding dead and stuck pixels in under a minute.
EIZO Monitor TestFreeWebA guided run through every panel test in one place. Good when you are in a hurry.
Keyboard CheckerFreeWebShows every key registering. Finds dead keys and chatter on a phone at the meet-up.
Key-TestFreeWebSecond opinion on key registration, and it shows rollover when you mash keys.
Mouse Rate CheckerFreeWebMeasures actual polling rate, plus buttons, scroll and double-click faults.

Power, cooling & fit06

CybeneticsFreeWebMeasured efficiency, ripple and noise for specific power supplies, across thousands of load points.
Hardware BustersFreeWebIndependent power-supply reviews and ranked picks from the lab behind Cybenetics.
PSU databaseFreeWebMaps a retail power-supply model to the OEM platform actually inside it. Brands rebadge; platforms do not.
Noctua socket chartFreeWebWhich cooler fits which socket, and which free upgrade bracket you need. The model other brands are judged against.
PCPartPickerFreeWebCatches clearance and compatibility problems — cooler height, radiator mounts, case and board fit — before you pay.
Network UPS ToolsFreeLinux / Mac / WinTalks to a UPS over USB: battery charge, load, runtime estimate and self-test results.

Control & tuning03

Display Driver UninstallerFreeWindowsStrips a graphics driver back to nothing, so your numbers are not someone else’s leftovers.
ThrottleStopFreeWindowsShows exactly why an Intel laptop is slowing down, and lets you undervolt it.
AMD Ryzen MasterFreeWindowsPer-core clocks, temperature and power limits on Ryzen, plus Curve Optimizer.

Where to find the baseline12

iFixitFreeWebTeardowns and parts availability. Tells you whether a worn part is a ten-minute swap or a mainboard job.
3DMark result searchFreeWebFilter millions of submitted runs by exact GPU and CPU to find your expected score.
TechPowerUp GPU databaseFreeWebEvery card ever made: real specs, memory type, TDP, and which die is actually inside.
GPU hierarchyFreeWebOne ranked ladder of graphics cards by measured game performance, kept current.
CPU hierarchyFreeWebThe same ladder for processors, split into gaming and productivity.
PassMark CPUFreeWebEnormous sample sizes and per-model score distributions. Good for spotting an outlier.
PassMark GPUFreeWebThe graphics-card half of the same database.
Gamers NexusFreeWebReviews with published methodology and error bars. Use their charts as your target.
RtingsFreeWebMeasured display data — response times, VRR range, real contrast — not marketing numbers.
HWBOTFreeWebOverclocker submissions. Useful for seeing what a part does at its ceiling.
r/buildapcFreeWebPost your numbers with your full spec and someone will tell you what is wrong.
r/hardwareFreeWebWhere the methodology arguments happen. Read before trusting any single review.

Only from the source

Download every one of these from the link above or the developer’s own site. Benchmarking and diagnostic tools are a favourite wrapper for bundled adware and worse, and the aggregator sites that rank above the real ones in search results are exactly where that happens.

Numbers beat adjectives.

Browse the marketplace →FAQs →Get a unit verified →

Before you start

What a benchmark can honestly tell you

What it cannot

The pointer used throughout this page

Whole systems

Components

Displays & peripherals

The eight steps

Everything else you might be buying

What the numbers mean

How to find your expected score

When a number is low, this is usually why

Take it with you

Identity & health07

Processor07

Graphics07

Memory05

Storage04

Real-world & frametimes05

Displays & peripherals07

Power, cooling & fit06

Control & tuning03

Where to find the baseline12