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Guide

How to test a CPU before selling it

By the RebootSemi inspection team · Updated · 6 min read

A processor either runs stable or it doesn’t, and half an hour with free tools tells you which. These are the checks a buyer runs when the chip arrives, so doing them first means no surprises about the offer.

1. Go back to stock settings

Test the chip the way its next owner will first run it. In the BIOS, load the optimised defaults — that clears any overclock or undervolt, including memory profiles such as XMP or EXPO, which can cause crashes that are not the processor’s fault. Update the BIOS first if an update is available.

2. Confirm the chip

Open CPU-Z and check the name, the core count and the socket match what you are selling. It is easy to list a 13700KF as a 13700K, and the two are priced differently. Where else to find the model.

3. Run a stress test

Hold every core at full load for 15 to 30 minutes with one of these:

  • Cinebench in its multi-core mode, set to run repeatedly for a fixed time.
  • OCCT, whose CPU test reports errors as well as crashes.
  • Prime95, the long-standing torture test — the heaviest of the three.

A healthy chip finishes without a crash, a freeze, a restart or a reported error.

4. Watch temperatures and errors

Keep HWiNFO open during the test. Modern chips are built to run hot under full load — AMD’s Ryzen 7000 chips target up to 95 °C by design — so a high reading alone is not a fault. What to look for:

  • The chip hitting its limit and dropping clock speed within seconds, which usually means the cooler is not seated or the paste has dried out.
  • WHEA errors, which HWiNFO counts and Windows logs in the Event Viewer — a sign of instability even without a crash.

Intel 13th and 14th Gen: a special case

Intel has confirmed an instability issue affecting some 13th and 14th Gen Core desktop processors and released BIOS microcode updates to address it. If yours is one of them, install the latest BIOS before testing. If it still crashes under load, it may be affected — check whether it is still covered by Intel’s warranty before you sell it.

5. Inspect pins and pads

  • AMD AM4 and older have pins on the chip. Look along the rows from the side: a slightly bent pin can usually be straightened, a snapped one can’t.
  • Intel LGA and AMD AM5 have flat gold pads on the chip and the pins in the motherboard socket. Look for deep scratches or burn marks on the pads.
  • Check the metal lid for cracks or chips at the edges, and the green substrate for damage.

If it fails

We pay for chips that work. Most models get no offer if they fail, and a few carry a broken price, which the form shows when you pick the model. If you’re shipping other parts, put a failed chip in the box and we’ll recycle it responsibly. If yours passes, take it out and pack it safely and see what it’s worth.

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