CPU test: performance and overheating

When to test the CPU

Test it when you look at a used laptop or phone, when a device feels slow, runs hot or the fan gets loud, and after a clean-out or new thermal paste to see if it helped. The test runs a heavy load continuously, so plug a laptop in and close other apps.

Common faults and their causes

• Performance drops sharply after a few seconds: the device is overheating and throttling. Usually dry thermal paste or a fan and vents full of dust, especially on a laptop that hasn't been cleaned in 2 or 3 years.
• Scores far below the same model: a worn battery making the device limit itself (iPhone may say so under Battery Health), battery saver turned on, or a laptop running on battery.
• Too hot to touch, a grinding fan: a worn fan bearing or a bent fan blade.

Scores also depend on the browser, so compare only with the same device (before and after a clean-out) or with the same model in the same browser. For wider comparisons, use the Geekbench links in the test.

What to do if you find a fault

• Turn off battery saver, plug in, let the device cool down and run it again.
• Laptop: cleaning the fan and replacing the thermal paste usually fixes throttling. See how to check a used laptop.
• If you suspect the battery, run the battery test.