The fan on the board (and the processor) sometimes decides to go nuts and works on max power. I look in the Task manager and there is no process that loads the CPU, HDD or the memory. The fan is clean (I checked and cleaned again, even though there was nothing to clean).
It just goes crazy, whenever it decides, and keeps the temp of the 2 CPU cores 30 - 45 degrees. And just goes down and up on the power of work, then on max for some time, then up-down and max again and so on.
Any ideas what might be the problem and how to solve it ? Just the constant sound is really annoying when I am working.
P.S. since there's no tag for the models, the laptop is ProBook 4520s. I bought it 2 years ago and have never had hardware problems with it.
EDIT: Forgot to say that I've changed the thermal paste just couple or 3 months ago.