CPU fan speed fluctuates in 2-3 second period

[SeryVlk]

The RPMs of the CPU fan regurarly fluctuates in the range of 100-150 up and down again. It does not depend on OS, as it can be observed even in the HP setup utility - BIOS setup (link to video is attached). It's happening on every level of load and fan speed, high or low. Produced 'waving' noise is really irritating. I've never met such behaviour of any of other HP laptops nor desktop PC. But this is my first AiO :). I don't know if it is standard behaviour of HP AiO PCs or some defect in the therma regulation circuit on board. (BIOS has been updated to latest version - no efect). Any suggestion or experience with such thing?

https://drive.google.com/file/d/1FuINCCT0eJO0dwYUxGQGwksJs7RYbgoH/view?usp=sharing

[Grzwacz]

Greetings,

Welcome to the forum.

I am not a HP employee.

This problem could be a fan problem (replace the fan), a MB thermal sensor problem, or a MB voltage problem.

I would try replacing the fan first. You could also reset the BIOS to defaults before doing any hardware modifications. Or pull the MB battery to reset CMOS.

Have you checked CPU temps for a possible correlation between CPU fan speed and CPU temps?

The fan should run at a fairly constant speed and then ramp up as CPU temps rise.

Contact HP Support (Link) if you are in warranty.

Regards

Regards