My PC was running normally, then became extremely slow and shut down. When I tried to start it again, the motherboard displayed a "CPU Fan speed error detected" warning and instructed me to check whether the CPU cooler was connected to the CPU_FAN header or adjust the fan-speed limit in UEFI/BIOS. I disabled the limit, but a few minutes later I heard an unusual noise inside the case and shut the computer down. I'm using a Corsair H90i liquid cooler and want to know how to safely check whether the pump or radiator fan is working without damaging the PC.
2 Answers
Open the case and visually inspect the cooler while the computer starts. You should be checking whether the radiator fan spins on its own; don’t rely on spinning it with your fingers as a test. Also listen for grinding, rattling, or intermittent noises, and make sure the pump and fan cables are firmly connected. If the fan is wobbling or the noise returns, stop using the PC and replace the faulty fan or cooler. Disabling the warning only hides the symptom—it doesn’t fix a cooling problem.
This warning usually means the motherboard isn’t detecting the CPU cooler properly. Since you have a Corsair H90i liquid cooler, check that the pump or its fan cable is connected to the correct CPU_FAN or AIO_PUMP header, depending on your motherboard’s instructions. With the side panel removed, briefly power the system on and confirm that the radiator fan spins and that the pump is operating. Don’t keep using the PC if the cooler isn’t working, because the CPU can overheat and shut the system down.
I tried booting it again and the warning disappeared, and the computer seemed to work normally. I’m still concerned that the cooler may be failing, though.
The cooler is a Corsair H90i. I wasn’t sure whether you meant checking the fan while the PC was running or turning it manually, but I’ll inspect it while starting the system and avoid running it if the fan or pump appears faulty.