I have a MSI G31TMP21 motherboard with 2GB DDR2 RAM. Intel P4 3.0Ghz processor. The fan on my processor seems to be always running on full speed. I changed the BIOS settings but to no vain.

Check to see what temperature your CPU has. You may need to reseat the fan.

I have checked the fan. It seems to be seated perfectly. Are there ways to seat the fan.

I think Tripredacus meant the heatsink.

Is it running full speed from the moment you turn it on (completely cold) or is it firing up after few minutes (and stay full speed) ?

Is the fan connected to the left or right fan-header? Did you check that is is the CPU- and not the system-fan- header?

When I switch the power on the fan starts running in full speed. I have checked the fan connections. It's connected to the CPU header. I did some changes in the bios. Now the fan stabilizes to normal speed but every now and then it gains full speed.

Presuming you are using the stock Intel heatsink/fan, the only reason it should be running full speed on that board is if your CPU starts running hot. I'd get some CPU temperature reading tool to run when you notice the speed pick up, to see what temperature you're getting. I believe that somewhere around 60-70c is the temp that this board will kick up the speed. Normally I'd recommend Intel Active Monitor, but I think it would reject an MSI board.

I'd get some CPU temperature reading tool to run when you notice the speed pick up, to see what temperature you're getting. ... ... Normally I'd recommend Intel Active Monitor, but I think it would reject an MSI board.

Get Core Temp for this. Works perfect on almost every modern CPU.

Check if it's blowing in the good direction. I once saw a fan mounted in the wrong direction with two air flows were cancelling each other. The CPU was constantly downstepping. Not sure if it had been replaced or came out of factory like that (FujitsuSiemens desktop). I was really lucky to notice that (I knew the front fan was supposed to suck air because some people were putting post cards on their computer and some were sticking and blocking the air entrance). The (warranty) tech must really have thought I was an expert . B)