Question : Problem: Computer sounds like CPU or PSU fan's RPM's are increasing, then decreasing every 2 seconds or so.

On one of our computers, it has started to make an annoying noise.

It will be normal sounding, quiet, some fan noise.

Then after two or so seconds it will sound like a fan's RPM's are going up very high, no matter what the load on the computer.

I cant tell for sure, i think its either mobo or PSU, but its extremely annoying.

When i watch the case, i cant see any noticeable speed changes on the CPU fan.

Ideas? It didn't make this sounds a while ago

Answer : Problem: Computer sounds like CPU or PSU fan's RPM's are increasing, then decreasing every 2 seconds or so.

you can determine if it is the cpu or PS fan, by inserting a piece of paper, and stopping it momentarily
post back the result