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How to check a used server
Ex-datacentre servers are the best value per core on the used market and the most frequently regretted purchase on it. The specifications are genuinely extraordinary for the money. The reason they are cheap is that they were built for a room nobody has at home.
The short answer
Before you look at a single specification, find out how loud it is and what it draws. A 2U server at full fan speed is roughly as loud as a vacuum cleaner and does not stop, and that — not the core count — is what decides whether this machine can live where you intend to put it.
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.AIDA64 ExtremeTrialWindowsThe memory bandwidth and latency benchmark everyone quotes. Trial period is enough.Cinebench 2026FreeWin / MacThe standard sustained CPU render test, single and multi-core, with a timed loop mode.smartmontoolsFreeWin / Mac / LinuxThe same SMART data from a terminal, on machines CrystalDiskInfo will not run on.CrystalDiskInfoFreeWindowsSMART data: drive health, power-on hours, total bytes written, link speed.
The things that send a server back to the seller
- Hear it run, at full fan speed, in a quiet room. Not a video — in person. Enterprise chassis ramp their fans to a level designed for a room with hearing protection policies, and many will run at high speed permanently if they detect a non-original part. If you cannot stand next to it during the test, you cannot put it in your home.
- Measure or calculate what it pulls at the wall, idle. Servers idle high by design — redundant supplies, many drives, full-speed fans. An idle draw of several hundred watts is an electricity bill, every hour, forever. Work out the monthly cost at your tariff before you commit; it frequently exceeds the purchase price within a year.
- Count the drive caddies, and confirm they are the correct ones. Enterprise chassis take model-specific caddies, blanks and interposers. Servers are routinely sold with drives pulled and caddies gone, and replacements cost real money per bay. A sixteen-bay chassis with four caddies is a four-bay server until you spend more.
- Check the RAID controller and, specifically, its battery or supercapacitor. A failed cache battery forces the controller into write-through mode, which collapses write performance and is a fault people spend weeks misattributing to disks. The part is a consumable and is often already dead on a machine of this age.
- Find out what the management controller needs to be useful. iDRAC, iLO and their equivalents have licence tiers, and the genuinely useful features — remote console, virtual media — usually sit behind the paid one. Without it you will need a monitor and keyboard physically attached, which defeats much of the point.
- Confirm the power supplies run on your mains, and that the leads match. Some enterprise supplies are 200-240V only, and some use C13/C14 or C19/C20 leads that do not come with the machine. Check the input range printed on the PSU itself against what is actually at your wall.
- Ask whether the rails are included, and which rails they are. Rack rails are model-specific, expensive, and almost never included. If the machine is going on a shelf that matters less — but a rack server on a shelf blocks its own airflow, which brings you back to the fans.
- Pull SMART on every drive with [smartmontools](https://www.smartmontools.org/). Enterprise drives run continuously for years. Five-figure power-on hours is normal here rather than alarming, but you need to know the number so you can price the replacements you will be making.
The one nobody checks
Noise, and it is not close. Every other item on this page is a cost you can absorb. Fan noise is the reason used servers get resold within a month — people buy on core count, put the machine in a spare room, and discover that enterprise thermal design assumes a datacentre where nobody sits. Hear it before you buy it. If the seller offers a video instead, the answer is no.
Note
Per core and per gigabyte of ECC memory, nothing else on the used market comes close. If you have somewhere genuinely isolated to put it, a cool room, and electricity you are not personally paying for, a used server is exceptional value. All three of those conditions have to be true, not two.
What to measure
Higher is better▲Higher is betterLower is better▼Lower is betterMust be zero∅Must be zeroMust match the spec=Must match the spec
What a used server really costs you
| Metric | Which way | What it tells you | Healthy looks like |
|---|---|---|---|
| Noise at full fan speed | Lower is better | The specification that decides where the machine can live. | Something you can tolerate through a wall. Be honest — it will not get quieter. |
| Idle draw at the wall | Lower is better | The running cost, which compounds. | Calculated against your tariff. Often the largest number in the purchase. |
| Drive caddies present | Higher is better | How many bays you can actually use. | One per bay you intend to fill, of the correct type for the chassis. |
| RAID cache battery health | Must match the spec | Whether writes run at full speed. | Healthy, or priced in. A dead one silently halves write performance. |
| Management licence tier | Must match the spec | Whether you can administer it without a monitor. | The tier that includes remote console, or a plan to live without it. |
| PSU input voltage range | Must match the spec | Whether it runs on your mains at all. | Covers your supply. Read the label on the unit, not the datasheet for the model. |
| Drive power-on hours | Lower is better | Remaining life in the consumables. | Known and priced. High hours is expected; unknown hours is not. |
| Rails included | Higher is better | A model-specific part that costs real money. | Present and correct for the chassis, if you are racking it. |
Walk away if
Walk away if
- A seller who will not let you hear it run at full speed.
- Empty bays with no caddies on a chassis that needs specific ones.
- A RAID controller with a dead cache battery.
- Management with no licence and no console access.
- Power supplies rated 200-240V only where you have neither.
- Fans that stay at maximum permanently because of a non-original part.
- An idle draw the seller cannot tell you.
What each fault is worth
Bring the measurement, not the opinion. Name the fault, name the fix, name what the fix costs — that is a solvable problem with two acceptable answers, which is what makes it work.
| What you found | What it actually costs | What to ask for |
|---|---|---|
| Missing caddies | Bays you cannot use. | Their real cost per bay, which is higher than expected. |
| Dead RAID cache battery | Write performance collapses. | The part cost, plus the diagnosis time you will otherwise lose. |
| No management licence | No remote console. | The licence cost, or accept a permanently attached monitor. |
| High idle draw | A recurring electricity bill. | Work out twelve months at your tariff and treat that as part of the price. |
| No rails | A model-specific, expensive part. | Full replacement cost, or a shelf and worse airflow. |
Ready to go looking?
Take the checklist with you, then browse what is listed. Everything on this page works just as well the other way round when you are the one selling.