CPU colling fan was spoilt. So installed a new one. To do so I had to remove the CPU cooler(heat Sink). Applid the thermal paste and resintalled the cooler. NOw the PC does not start at all. Not even the BIOS msg..
In the mean time I figured out the problem and fixed it. Probably the thermal compound that I applied was a little more and was causing the pins to short. I cleaned the socket and the CPU with spirit and using a vaccum cleaner. That fixed the problem.
Interestingly I also realized that there was nothing wrong with the fan either. Probably the heat sink (CPU cooler) was not sitting firm on the CPU as the thermal compound had hardened after 5 years of use and come off loose causing the CPU to heat up and in turn causing the fan to blow much faster. I have reinstalled the original fan and everything is fine.
In summary..If the CPU fan blows too fast and makes noise. Just try cleanig the cooler contact with the CPU with spirit and apply very little thermal compound and remount the cooler. This might fix the problem. Thermal compund should be applied in as little quantity as possible as it gets squeezed between flat surfaces of cooler and CPU and may spill over. Hope someone camn benefit from my exprience..Vivek