What controls the speed of the CPU fan?

[trots]

My cpu fan seems to have slowed down lately. It used to run between 3500-4600 rpm, now when I check it's usually at 2570. Not surpisingly my CPU temp has risen, from around 49 to around 55. If I open up the case and just move the cables and wires around then check again, it'll be back up over 4000 but eventually slow back down to 2570 again and stay there.

What's making it "think" it should run slower now? Any ideas on how to speed it back up?

 

[Goi]

Dust accumulation perhaps? Or a lower current than normal?

 

[trots]

Okay, I'm an idiot. I had the thermocouple taped to the Via Northbrige heatsink instead of the CPU's. Duh, I mean they're about the same size (just kidding).

Anyway, it turns out my CPU is running around 38C, so I'm not as worring now. I also got the case temp to drop a couple (to 26) just by clearing the cables for a better air path.

Thanks.