Cpu Fan

hi,
i got a P4 1.7Ghz. Intel motherboard. When i start my computer the fan speed is around 1500Rpm. this causes a seriously worrying noise. after about 5-10mins it goes back to normal (about 3800-4000Rpm), normally my CPU temp is around 35-40 C. Why does it do this? Is this gonna mess up my CPU? Please Help

 

Its probably a control mechanism... when the machine starts up it runs it slowly as the CPU isnt that hot yet, it wont spin the fan as fast, as its not required (a waste of energy). But of course as you use your computer the temperature will go up, and so the fan will speed up to compensate.

If it makes a grinding noise, then that might mean the bearing is begining to wear, which means you might need to get a new fan soon. If its just a low pitched noise, you should be fine.