After not using my M6600 for a couple of years, I have decided to give it some relatively intensive computation to do. However, I can hear the fan at full speed for a couple of seconds, then stopping for another couple of seconds, and so on without interruption.
As you can see from the screenshot below, the fan speed closely follows the CPU temperature (as one would expect), and they both go up and down in very short cycles of large amplitude, from 64 celsius to 91 celsius (which seem too high).
I have updated the BIOS, but the problem persists. Do you know what I should do?
Given the 5-6 year age of the system, remove and clean the heatsink assembly and thermal compound under it - then replace the thermal compound and reseat the heatsink. The compound is probably dried out and preventing the heatsink from doing its job.