Buying a used gaming PC is one of the better ways to get a lot of performance for your money, and one of the easier ways to buy somebody else’s problem. The advert lists a strong graphics card and a recent processor, the photos show a glass panel full of coloured lights, and the seller is twenty minutes away. We see the results of these purchases at our Edinburgh workshop every month, including from Tranent and the rest of East Lothian, and the same handful of faults turn up again and again.
This guide is the checklist we would use ourselves: what to ask before you travel, what to look at in the seller’s front room, the quick tests that catch most bad machines, and what to do in the first week once it is yours.
Before You Travel: Questions Worth Asking
A good seller answers these without fuss.
- The exact parts, not the headline. Ask for the model of the processor, graphics card, motherboard and power supply, plus how much memory and what size and type of drive. “RTX gaming PC” is not a specification.
- Who built it. A machine from a big-brand manufacturer, a system builder, or assembled at home are three different things, and it matters later for upgrades.
- How old each part is. Gaming PCs are often a newer graphics card dropped into a much older system. Receipts or order emails settle the question.
- Why it is being sold, and whether it has been repaired. You are listening for how the answer is given as much as for what is said.
- Whether you can see it running a game. If the answer is no, or the PC is “already boxed up”, treat that as the answer to every other question.
Check the age of the platform while you are at it. Windows 10 is out of support, and Windows 11 officially needs a processor from roughly the last seven or eight years plus TPM 2.0. A used PC that cannot run Windows 11 properly is a short-lived purchase however fast it looks on paper.
The Fault We See Most: A Good PC With a Poor Power Supply
If we had to name one pattern from the bench, it is this. The graphics card and processor are exactly as advertised, and they are fed by an unbranded power supply that was never suited to them. Nobody lists the power supply in an advert, so it is the part that gets skimped on when a PC is built to sell, or swapped out before a sale.
A typical example: a gaming PC bought through an online marketplace and brought to us a fortnight later. It sat on the Windows desktop all day without complaint and switched itself off a few minutes into any game. The card was fine. The power supply was a no-name unit rated well below what that card draws under load.
So look at the label. It is usually visible through the side panel or from the back of the case. You want a manufacturer you can look up, a wattage that suits the graphics card, and an efficiency rating printed on it. A blank grey box with no brand is a reason to walk away or to budget for a replacement straight away. Our guide to the warning signs of a failing PC power supply covers what the symptoms look like once you own it.
What to Look At Before It Is Switched On
- Dust and general care. A layer of dust is normal and cleans off. Matted filters, sticky residue or a smell of smoke tell you how the machine has lived.
- The graphics card. Check it sits level in its slot and is screwed to the case. A heavy card that has sagged for years strains the slot. Look at the fans for cracked blades and at the backplate for heat discolouration.
- Liquid cooling. Sealed liquid coolers have a pump that wears out. On an older system, ask how old the cooler is and listen for gurgling or rattling once it runs.
- Ports and panels. Try the front USB and headphone sockets, and check that the side panels, screws and any dust filters are all present.
- Memory. Two matching sticks are what you want to see. A single stick holds back a gaming PC more than most people expect.
Tests You Can Run in the Seller’s Front Room
None of these needs extra software, and together they take about twenty minutes.
Confirm the Parts Match the Advert
Press Ctrl, Shift and Esc to open Task Manager and choose the Performance tab. The processor, the amount of memory, the drives and the graphics card are all named there. Compare each one with the listing.
Check where the monitor cable goes as well. It should be plugged into the graphics card, lower down the back of the case, not into the motherboard sockets near the top. A PC demonstrated from the motherboard socket may not be using the card at all.
Play Something Demanding for Fifteen Minutes
This is the test that matters most, because most faults in a gaming PC only show under load. A machine that idles happily tells you very little. Ask the seller to start a recent game and leave it running while you talk.
Watch for flickering, coloured blocks or sparkles on screen, sudden stutter after a smooth start, fans that climb to a roar, or the PC switching off or restarting. Any of those is a real fault and not a setting. Our guide to the signs a graphics card is failing explains what each kind of on-screen glitch points to.
Check the Drive and the Windows Licence
In Windows 11, open Settings, then System, Storage, Advanced storage settings, and Disks & volumes. Choose the main drive and open its properties. For most modern SSDs Windows shows an estimated remaining life and a temperature. A drive reported as worn or in warning needs replacing, and your offer should reflect that.
Then open Settings, System, Activation. It should say Windows is activated. If it is not, the licence did not come with the PC.
Ask the Seller to Open the BIOS
Have them restart and press the key that opens the motherboard settings. If a password prompt appears and they cannot get past it, you would be buying a machine you cannot fully control.
Ex-Mining Graphics Cards: Not the Deal-Breaker People Think
Most guides tell you to avoid any card that was used for cryptocurrency mining. On the bench the picture is more mixed. A mining card has run for long hours at a steady load, which is easier on the electronics than years of heating up and cooling down in a gaming PC.
What wears out is the moving and perishable parts: the fan bearings, the thermal paste and the thermal pads. A card that runs hot and loud but produces a clean picture is often a servicing job. A card that shows artefacts under load is not, and no amount of new paste will fix it.
Big-Brand Prebuilts and the Upgrade Trap
This is the judgement call a generic checklist misses. Some big-brand desktop PCs use their own shape of motherboard, their own power supply connectors and a case with little spare room. They work well as sold, but the day you want a stronger graphics card you can find that a standard power supply will not plug in and a longer card will not fit.
If your plan is to buy used and improve it over time, a PC made from standard, off-the-shelf parts is the safer base. When one of those has a single weak component, a targeted hardware upgrade is straightforward: more memory, a larger SSD or a properly rated power supply.
If the power supply turns out to be the weak link, you can see current options in the power supplies section of our shop.
The First Week: What to Do Once It Is Yours
Do not carry on using the seller’s copy of Windows. You have no idea what is installed on it, whether their accounts are still signed in, or what has been switched off to make games run. Wipe the drive and start again. Our walk-through of how to clean install Windows 11 covers it step by step, and if you would rather hand it over, our Windows installation service includes drivers and updates.
After that, open the case and clean it out, set the memory to its rated speed in the BIOS (the setting is called XMP or EXPO), and keep an eye on temperatures during the first few long sessions. If anything is going to show up, it normally shows up in that first week.
Bear in mind that a private sale gives you far less comeback than buying from a business. The PC has to match its description, and that is about all. That is the real reason to do the checks before you pay and not after.
When a New Build Makes More Sense
Sometimes the sums do not favour used. If the machine needs a power supply, a drive and a cooler to be trustworthy, you have bought a case and a graphics card with a project attached. At that point it is worth comparing against a custom PC build, where every part is new, chosen to work together and tested under load before you see it.
A sensible middle route is common too: keep a good used graphics card and build a new system around it. You can sketch a parts list in our PC Builder to see how the two routes compare. Our page on custom-built computers in Tranent explains how a build is planned and delivered locally.
Getting a Used Gaming PC Checked Near Tranent
If you have already bought one and something is not right, the quickest way to an answer is a bench test under load. We check the power supply, temperatures, drive health and the graphics card properly, and tell you plainly what is sound and what is not before any work is agreed.
Our workshop is at 140 Parkhead Drive on the west side of Edinburgh, a straight run along the A1 and the bypass from East Lothian. A desktop tower is an awkward thing to move, so we can collect from anywhere in EH33. See our gaming PC repair in Tranent page for how that works, or book a diagnosis online and tell us what the PC does under load.
Whether you are in Tranent, Prestonpans, Musselburgh or Haddington, the rule is the same: see it run a game, read the power supply label, and reinstall Windows before you trust it.
Last updated: 6 October 2026