I left my PC turned off throughout the summer because the room was extremely hot. After turning it on again once the weather cooled down, it ran for about an hour before suddenly shutting off. Now it powers off whenever I open almost any application. At idle, with no tabs or apps open, the CPU sits around 89–90°C, and with a browser open it approaches 100°C. I have three case fans, including one CPU cooler fan. Could I simply need better fans, or is there likely a problem with the CPU cooler or thermal paste?
3 Answers
Those temperatures point to a CPU cooler problem rather than a lack of case fans. Check whether the CPU cooler fan is spinning and whether its cable is connected to the CPU_FAN header. If you use an all-in-one liquid cooler, the pump could have failed, become clogged, or trapped an air bubble. Avoid using the computer much until this is fixed, since it is shutting down to protect itself.
Replacing thermal paste is inexpensive and usually straightforward. Shut the PC down, unplug it, and let the CPU cool. Remove the cooler, clean the old paste from both surfaces with isopropyl alcohol and a lint-free cloth or coffee filter, then apply a small pea-sized amount of new paste to the CPU and reinstall the cooler evenly. Be careful not to pull the cooler off forcefully if the paste has hardened; gently twist it first. If you have a liquid cooler, repasting will not help if the pump itself has failed.
Inspect the cooler carefully. Make sure the heatsink is firmly mounted, the protective film was removed before installation, and there is thermal paste between the cooler and CPU. If the fan is spinning but temperatures remain near 90°C at idle, removing and reinstalling the cooler with fresh paste is a sensible next step.
All of the fans are spinning, so I’m going to check the cooler mounting and replace the thermal paste. I’ve never done that before, though—what’s the safest way?