How to test a used GPU

The point of testing is to use the return window

Nearly every problem a used graphics card can have will show itself within an hour of deliberate load. Nearly none of them will show themselves while you browse the web for three weeks and then discover the card is faulty on day 31. So the procedure below is not about being thorough for its own sake — it's about converting a return window you have into information you don't.

This is the same sequence we run on every card before listing it. It takes about an hour, most of which is waiting.

1. Inspect it before it goes anywhere near a slot

• Spin each fan by hand. It should turn freely, without grinding or catching.
• Look along the PCB for scorch marks, bulging capacitors, lifted components, or the dull grey residue of a repair.
• Check the PCIe connector edge for deep scoring, and the display outputs for bent or pushed-in pins.
• Look at the bracket and the card body for the kind of bend that means it was dropped.

Anything here that looks wrong is worth stopping for. It's much easier to return a card you haven't installed.

2. Install clean drivers

Remove the existing display drivers properly rather than installing over the top — a leftover driver from a different vendor produces crashes that look exactly like failing hardware and will send you chasing the wrong problem. Then install the current driver for the card.

3. Confirm the card is what the listing said

Use a hardware information tool to check the actual GPU model, the memory size, and the memory type. This catches two things: an honest mistake in the listing, and the rare but real case of a card flashed or relabelled to look like a higher model. Compare what the software reports against what you paid for.

4. Load it, properly, for twenty to thirty minutes

A five-minute benchmark proves almost nothing. What you want is sustained load long enough for the card to reach its steady-state temperature and stay there. A looping graphics benchmark or a demanding game at high settings both work. While it runs, watch for:

• Visual artifacts — flickering triangles, stray coloured pixels, textures tearing into geometric noise. This is the classic signature of failing memory and it is a hard fail.
• Driver resets or crashes to desktop. Occasional on a healthy system; repeated under load is not.
• Hard lockups or reboots, which can also mean the power supply isn't up to the card — worth ruling out before blaming the GPU.

5. Watch the temperatures and the fans

Log the temperature through the load test. What you're looking for is a card that climbs to a plateau and holds it. Warning signs are a temperature that keeps climbing until performance drops off a cliff, a large gap between the core and memory-junction readings where the card reports both, or a fan that never spins up, spins erratically, or gets audibly worse as it warms. Note that a specific temperature target varies a lot by model and cooler design — the shape of the curve tells you more than the number.

6. Test every output

Plug a display into each port in turn. A dead HDMI port on an otherwise perfect card is easy to miss and impossible to fix.

What each result means

• Clean run, stable temperatures, all outputs working: keep it. A card that survives sustained load has told you everything a used buyer can know.
• Artifacts or repeated crashes under load: return it. Underclocking can sometimes mask memory faults; it doesn't fix them.
• Runs fine but very hot, with a tired-sounding fan: negotiable. Fans are replaceable and thermal paste is renewable — but only take this on if you wanted the project and the price reflects it.