CPU Fan Problems. Can't set minimum speed.

[kmenc]

My CPU fan recently started slowing to a stop and then roaring back over and over. It only does this under light loads and idle, not when, for example, I am playing a video on youtube, or some other similar load activity. On high loads, the fan keeps moving. The CPU is NOT overheating. In fact, all temps are quite low. (10C-30C) Checking with various fan monitoring software I noticed there is no minimum speed set for that fan. I have replaced the stock Coolermaster fan with a new identical one - no change. I removed the heatsink, cleaned everything and reinstalled with fresh thermal paste - no change. I will sometimes get the 90B "fan not working properly" error on reboot, but not all the time. I updated the BIOS to the latest version and tried to set a minimum speed under the Thermal tab, but it only displays the current speed and does not let me set a minimum. Seems to me its stopping because it senses the temps are low and the fan isnt needed then roars back to life and that if a minimum value were set, everything would be fine. This is extremely annoying and only started recently. Bad Windows or driver update? I dont know what to do or where else to look. Plz help.

[praveenbv]

@kmenc

I would recommend is contacting HP to see what your options are regarding service. Perhaps the bearing of the fan is faulty or the cooling paste might need replacing.

You could also try using a can of compressed air to blow out any dust from the inside. 

 Keep me posted. 

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[Jay891]

I would be suspicious of temps that low unless the computer was in a freezer.

I had similar issues with an HP pavilion desktop and the problem went away when I switched to a different brand motherboard with fan Xpert fan control software.

Because basically the HP motherboard sent erraric temperature readings and the fan profile is not able to be edited by the user.  

Could be malware too.  Some improper software installs miners that seem to make the fan behave erratically mainly around login / logout, inactivity vs actively using the PC.

[praveenbv]

@Jay891, Yes, it can use the same steps for desktop 

malware check I suggest to malware bits or Antivirus  scan