HP Elitebook 840 G5, Fan always running on 100 %, Win 11

[Ollsbols]

I have the same issue. It is pretty dreadful. I have replaced the thermal paste on the CPU and it has made no difference. I didn't expect it to as the fan runs at 100% when generating no heat and no programmes running.

[TzortzisG]

Hello Ollsbols.

Based on my experience with several HP laptops I've used throughout the years, the HP BIOS fan profiles use 2 or 3 different sensors to control the fan's behaviour. If one of these sensors malfunctions, then the HP BIOS will (for safety reasons) lock the fan to its max speed. You can use some monitoring program like HWiNFO to see if the damaged sensor shows up, but many times these sensors aren't visible to 3rd party software.

In these cases the only real fix is a complete motherboard replacement, which would mean finding a used motherboard online or harvesting one from a refurb. There is a possible workaround however. You can try to take control of the fan. The third party tool Notebook Fan Control (revive) should work. For Windows 11 and/or Intel 10th Gen and up I strongly advise using the latest OpenHardwareMonitorLib plugin according to these instructions. Install the program, replace with the updated file, and run it. The fan profile for Elitebook 850 G5 should work perfectly for you.

If the CPU temp sensor isn't the one with the issue, you can use the nbfc settings to have a fan that reacts to temperature increases and get the system to work in an almost normal way. Otherwise, you will have to manually control the fan's speed, or set it permanently to a more sensible speed (20%, 50%) according to your preferences.

Post back if you have more questions.