Processor problem or windows.

I start the computer,all fine.After loading screen in window system start to load all start up program and others.After this process i can hear a sound like you start the computer, that sound before the POST screen.I have monitorized processor from task manager and CPU usage is goind to 0% when is doing that.
I've checked the processor cooler and the thermal conductive paste, in half of part was like an water mixed with paste and the second half is normal.The cooler is well fixed there.Is doing 4-5 times then will stop and working normal, maybe after some hours to begin doing like that...idk what is going there but must be the processor or something near it.