Sudden change in cpu temp

I've had a P4 3.0Ghz for sometime now and it's been working without problems untill recently. I've used MBM 5 and Hardware Doctor to monitor the temps on the computer during this time aswell. No clocking and no fiddling has been done.

And here is the problem. A few weeks ago i noticed that my cpu was running alot hotter then before, the change came almost overnight so it probably has nothing to do with dust or the like. It used to run at a maximum 61C, now it exceedes 70C and alarms start going off if i have the computer at max for a while.

One thing i've noticed is that before MBM used to report the cpu fan speed at about 2700rpm when the computer was idle and then when the cpu got maxed out the speed rose to about 3500rpm. Now the speed goes from 2700rpm to 2900rpm. This could be one reason for the sudden temp change, however, the fan sounds just like it did before when the speed changed, so i'm not all conviced that the MBM has the speed correct. And if the fanspeed really has changed, what made it do it? And how do i revert to the way it was before? As far as i can remember i hadn't fiddled with anything that has to do with fanspeeds or temps before the change happened. The fan seems to be working fine except for this so i don't think it's breaking down or anything.

I think you're on the right track. It could be dust. Did you open up the case and see what's going on in there? CPU fans are pretty cheap if you want to replace yours. If you're running with a thermal sensor maybe it's not working right. Try to bypass the sensor and run the fan at full speed. Make sure all your input/exhaust fans are working properly too.

If you recently moved it recently maybe something done broke. Check that your heatsink is still making good contact with the CPU.

You fan speed went from 2700 to 2900rpm because the cpu is hot and its trying to cool it. The fan hasnt lost speed its gained speed. Try taking the heatsink off and cleaning it and the processor and then put new thermal gel on it. You can also update your bios but make that the last thing you try.