Testing a second-hand PC before you buy

A used PC can be a great deal, but only if it works as described. Half an hour of testing at the viewing catches most problems. Take this checklist with you.

Before you go

• Ask the seller to run our spec summary script and send you the result, or a screenshot of the specs.
• Ask about its history: how old it is, whether it's been overclocked or used for crypto mining, and whether anything has been replaced or repaired.
• Agree that you'll see it running and test it before you pay.
• Bring a USB stick with free portable tools: CPU-Z, GPU-Z, HWiNFO and CrystalDiskInfo. Headphones are useful too.
• Read our Stay Safe guide about meeting up and paying.

At the viewing

1. Check the specs match the listing. Open Task Manager (Ctrl+Shift+Esc → Performance), then confirm in CPU-Z and GPU-Z. GPU-Z also warns if a graphics card's details look fake.
2. Stress test it for 10–15 minutes. Run a demanding game or a free benchmark such as Unigine Superposition (graphics) or Cinebench (processor). Watch the temperatures in HWiNFO. As a rough guide, the processor should stay below about 90°C and the graphics card below about 85°C. There should be no crashes, freezes or flickering shapes on screen.
3. Check the drives. CrystalDiskInfo should show every drive as "Good". Look at the power-on hours to see how much it's been used.
4. Listen. Grinding fans or a loud high-pitched whine under load can mean worn fans or a failing power supply.
5. Try the ports. Plug something into every USB port, and check the network, Wi-Fi, Bluetooth and audio.
6. Check Windows is activated in Settings → System → Activation.
7. Make sure it isn't locked. There should be no BIOS password, and no work or school management (Settings → Accounts → Access work or school). On a Mac, the seller must sign out of Find My before you pay.
8. Look inside if you can. Check for heavy dust, damage, and the make and model of the power supply. An unbranded power supply in a high-end PC is a warning sign.

Extra checks for laptops

• Check the screen on a plain white and a plain black background for dead pixels or marks.
• Try every key and the trackpad, and open and close the lid to check the hinges.
• Check battery health: run powercfg /batteryreport in Command Prompt and compare "Full charge capacity" with "Design capacity".
• Make sure the charger is the right one for the laptop.

Is it stolen?

Ask for the original receipt, and check the serial number on the case matches it. Be cautious if the seller can't explain where it came from, won't meet at an address, or the price seems too good to be true. If you're suspicious, don't buy it, and report the listing.

Paying

Only pay once you've tested it and you're happy. Pay in person, by cash or an instant bank transfer while you're together. Ask for a simple receipt with the seller's name, the date, the item and the price. If you're buying from a business seller, you have extra rights under the Consumer Rights Act 2015.