511-CPU fan not detected

[MJM76]

About 10 days ago I received the 511-CPU fan not detected at startup with F1 boot at the bottom of the page. Hit F1 and system started successfully. Have not had any performance issues that I'm aware of since that incident. Opened the case today and found a dirty CPU fan that turned freely. Cleaned it with compressed air. Plugged the power cord back in and turned the unit back on. The other fans ran at startup but the CPU fan did not run.  I powered the unit off and unplugged the power cord. Plugged in the monitor and external hard drives and plugged the power cord back to the PC.  Got the 511 error message again. Hit F1 and system booted up just fine. Continues to run without any issues. 

Is this simply a bad CPU fan that needs to be replaced or could there be something else going on?  PC is almost 5 years old and sees daily usage with relatively light duty. 

Thanks for your thoughts!

[old_geekster]

@MJM76 , welcome to the Community.

Without being able to inspect the fan, I believe that it is most likely the bearings failing.  Sometimes when dust gets heavy on the fan it can get into the bearings.  I suggest replacing the fan.

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