What could be causing my PC's fan to intermittently whir for brief period of time?

Question

I have a Dell XPS 400 PC running Windows 7. Every so often (45 minutes or so?), the fan will make a whirring noise. It is intense, but lasts about three seconds. I'm trying to figure out why this is happening. This occurs even when the machine is not being used, or is in "Sleep" mode.

One thought I had was that a scheduled task was running. I looked through the Task Scheduler, but nothing sticks out as causing the problem. Is there a way to see a log of all tasks run?

Answer 1

My HP did something similar until I cleaned out the dust and fluff fron the air inlets and the heatsink over the processor. As it's in the bedroom I guess that contributes! I clean it out every couple of months now and so far no more frantic fan. Check that there is external space round the casing as well to allow air flow.