Fan Constantly Runs At Full Thottle

kflash08 · ‎11-30-2020

Since 2019, the fan on my HP 250 G4 constantly runs at full throttle. It started out as "revving" at first, but now constantly runs at 100% all the time, even right when I turn the computer on after its been off for a few hours. Very occasionally, the fan will spin down and operate normally for a few days, after which it will start to rev again and revert back to spinning at 100% all the time. It is not overheating. I've confirmed this by actually putting my finger on the heat sink assembly right above the CPU while the computer is running, and it's cool to the touch.

Here's what I've done...

Monitor temps and CPU usage (OK)
Blew the dust out of the heat sink
Reapplied the thermal paste between the heat sink and CPU
Reconnected the fan
Cleared CMOS (removed internal battery)
Reinstall Windows 10 (clean install)
Replaced external battery (old one was failing and causing the power adapter to randomly disconnect, so i thought that was related)
Upgraded HDD to a SSD a few weeks ago
Tested fan in HP Diagnostics under component tests (says not supported)
Tried adjusting settings with CoolSense

I believe this all started after a BIOS update, 28 or 29 if I remember correctly. Currently it has the latest BIOS version installed (31). I don't know what else to try, and I seriously doubt that replacing the fan will solve the issue. Any suggestions?