90B fan error, constant fan surging, all temps good

[NorcalGabriel]

I'm getting Error 90B at startup. I am also getting a lot surging from the CPU fan. It is usually around 1000, then will surge to near 4000. Sometimes it wont happen for hours, othertimes (like now) it will do it every 3 seconds over and over. Right now its going full speed for 1 second then regular speed for about 3 seconds, then totally stopped for 1 second, repeat. Its loud enough that I can't use my computer without headphones on.

Temps are all low. Core temps dont go above 100F , inside case is cool, air from case is cool, bedroom is cool,  no performance issues with computer. The only issues are the error on startup and the surging of the fan.

Things I have done - Used blower to clean out inside of computer, and fan. Everything is like new in there but was also pretty clean when the error started last week. I verified the fan is all properly installed and tightened, it seems like its in perfect shape. I doublechecked all my drivers are up to date, along with everything else.

What can I do? I cant find the fan for sale anywhere, and as far as I can tell there is no way of contacting HP to get a fan.

[Houda1]

Helo,

I invite you to check the bios drivers if it is up to date or not  and that by checking on the hp website.
As soon as you get the eraser message 90b, please press "enter " to access windows and update the bios.
In case the problem is same  and you notice that the machine overheats, I invite you to contact the support hp
If the machine is in warranty and the concern is taken care of it will be repaired
Otherwise, you will pay a quote (subject to process hp).

Regards ,

Houda