My system: AMD 64 3200 Nvidia 6800 PC2100 512MB RAM 40GB HDD Gigabyte K8VT800M New 550 Antec TruePower PS Yesterday I received new power supply and a new cpu fan with heatsink Installed the power supply, checked everything..computer ran fine, boot up and all... Then I started replacing cpu fan (doing it 1st time)...when I got fan+sink off, cpu came off with it....thermal paste was sticked to the heatsink with cpu...and looks like I pulled cpu off the socket without releasing that thing that goes on socket (you lower or upper it if you want to release/place cpu).. Cpu didnt seem damaged, looked fine and no visible damage...so I put it back in, put new heatsink fan, put everything back together - and COMPUTER DOES NOT BOOT...no CMOS screen, nothing..Power turns on though...I can see CDROM's light flashing, then I can see greenlight on my case light on..also when I power on I see yellow light for a couple of seconds and than it goes off...Did not see any HDD lights coming (red one)... I think Ive messed up my CPU...I also tried changing video cards - did not work... Do you think my CPU needs a replacement or I did something worse ? Is there any way to check that before I go spend 200 bucks on CPU ? Please help!

If you pulled CPU without releasing the lever, there is a possibility that the CPU might have been damaged, but you may be lucky and it may not have been. The easiest way to isolate the problem will be to swap processors if you have a spare. If that is not an option, remove the CMOS battery and all everything plugged into the board then with just the CPU, memory and the CMOS battery back in place power on and see if that works.

It is all too common to have P4 CPU stuck to the heatsink when replacing the heatsink. When AMD A64 began using the heat spreader, it too has the same problem. If pins are straight and no damage, unplug the power supply or reset CMOS. Most 865/875 boards will require resetting BIOS with no need to reset CMOS; for AMD you almost have to.

I also noticed you use PC2100 instead of PC3200. Make sure you set HTT correctly in BIOS.

Thanks for replies,guys. I tried resetting CMOS (taking out the battery)..Still, did not work..So far, socket doesnt seem to be damaged neither the processor..no beeps, nothing.. When I turn power on, my monitor displays msg "Video cable is not connected"...dunno what to do..maybe bring it to comp shop to fix because I dont wanna do anymore of experimenting :)