4 Methods on How To Fix CPU Fan Error on Boot But Fan is Running

By: Editorial Team

Typically, when your PC displays a CPU fan error on boot, you expect that the fan isn’t running. The error is a safeguard to protect your CPU from overheating when the fan is malfunctioning.

However, you’ll occasionally get a CPU fan error on boot even when the fan is running.

What does this error mean? Is the BIOS struggling to detect the CPU fan? Is it a false alarm, and do you ignore it? These questions and more are answered below.

Why Your PC Displaying CPU Fan Error But Fan is Working?

Here the problem often boils down to these causes:

  • Incorrect fan settings
  • Slower fan due to dust buildup
  • Lower RPM than the default
  • False alarm

How to Fix CPU Fan Error on Boot But Fan is Running

Dealing with CPU fan errors is always an elimination process. You’ll likely attempt all the fixes before you figure out the cause and remedy. Here are possible CPU fan error fixes:

Lower CPU Fan RPM

What’s the default CPU Fan RPM of your PC? The norm is 600 RPM, and the system expects the CPU fan to start at such speeds. If it boots at speeds lower than 600 RPM, it will trigger the CPU fan alert.

For example, if your CPU fan starts at 400 RPM, it will set off the error notification. Clearly, your CPU fan is running, but the speeds are lower than the preset RPM.

Lower the RPM to about 400-500 RPM and test if the system can detect the fan.

Open BIOS settings and change the default RPM to a lower figure.

Clean CPU Fan

The gradual accumulation of dirt can slow down CPU fans; thus, lowering the speeds below the preset RPM. Your CPU fan could be functioning, but it’s running too slow. This often affects CPU fans that are rarely maintained or cleaned.

It doesn’t take much to clean a CPU fan. You’ll need screwdrivers and compressed air. Open the case and clean the fans. Also, add some machine oil to the fan bearings. Once done, close the CPU fan and boot your PC.

Incorrect Installation

It’s possible that your CPU fan is plugged in the wrong header on the motherboard. Switching it to the correct fan can disable the CPU fan error on boot.

Some have also noted success after switching the headers, booting the PC, and then switching them back.

Disable BIOS Settings

Have you attempted the other fixes without success? Have you tested your CPU fan on another PC? If the tests have proven that the CPU fan is functional, you can disable monitoring in BIOS settings.

Your CPU fan can continue running without the annoying errors. Don’t disable the monitoring and alert settings if your CPU fan isn’t running fast enough to cool the CPU.

If you do, the CPU will continue overheating, and without a fully functioning fan, it will get damaged.

Change the alert settings to ignore by booting in BIOS. Open advanced settings and select the monitoring tab. Change CPU fan speed limit to ignore and confirm changes—exit and boot PC.

Final Thoughts

If these fixes fail to work, try getting professional assistance from a local service center.