Power cut causes CPU fan to reach maximum speed instantly.
Power cut causes CPU fan to reach maximum speed instantly.
We experienced a power interruption yesterday. Upon returning home and powering on the PC, the CPU fan reached around 1700 rpm (confirmed via HWinfo) and emitted a loud noise as if attempting to detach from the cooler. After rebooting, the fan stabilized at normal speed for roughly five hours. Near midnight it spiked back up to 1700 again. I powered off the machine overnight instead of attempting further fixes. Throughout this period, CPU temperatures remained within acceptable ranges, and I avoided any heavy tasks. No significant loads were applied—just browsing and watching videos. Anyone have insights or troubleshooting ideas? Have you encountered a similar issue before? Could replacing the fan or cooler resolve the problem? I’m also considering swapping to a different fan connector, as the available connectors can be mapped to temperature-based curves in BIOS. Let me know if you need additional guidance.
Changed the fan settings to the "CPU_OPT" option – the problem stopped for a while, then returned and then disappeared again later. It seems like the issue is with the fan itself. Likely just needs replacement unless someone offers a better idea.
After further checking, it turned out to be one of the case fans next to the CPU fan, not the CPU fan directly. Removed it, leaving two intake fans, and everything resolved.
When you explained it, it seemed like a bearing failed in one of the fans. Great job fixing it, and it should only cost around $15 for a new fan.