IS MY CPU DEAD

I am having similar problems, still not sorted, but I would suggest going to the motherboard manufactures web site (if not already done so) and see if they have any similar problems

Do a search for the motherboard model, look for any updates and look in the FAQ section

If no help, look for a diagram of the motherboard, and (making sure you use a H/D that has no vital data on, try resetting the bios jumper (following the instructions exactly)

Although I am currently having problems with one particular old PC, I have previously had same problem and solved it by either re-seating all cards etc, dong a boot with only very minimal cards/drives in place and if all this fails, resetting the bios

Well, did you remove the CPU with the computer plugged in?

If so, it is possible that the CPU is damaged.
Even when turned off, a modern PC still has power on the motherboard.

Did you disconnect the slave drive?

Did you set the master drive jumper back to single?

Many hard drives have different jumper settings for single and master with slave present.

Next, try reseting the CMOS memory.
Either set the jumper on the motherboard to clear, or unplug the PC and remove the CMOS battery for at least 30 minutes.

See if you can now boot.
If so, enter BIOS setup and make sure that the CPU settings are correct.
Then install the battery before shutting the PC down.

Chas

The motherboard may be set to halt on all errors. So if the drive was incorrectly installed then the system may just be protecting itself.

Is the drive an ATA 100/133 drive and needs 80 wire ribbon cable with the end with the colored connector on the motherboard. Is the jumper settings on the drives correct.

Put the system back together like it was before you had the problem. If it doesn't start do as Chas said clear the CMOS. You've probably broken the seal between the CPU and heatsink for the fan so it would be a good thing to get some heatsink grease and put a drop or two on.