UPDATED Computer turns on and shuts off within 1-2 seconds

[A Casual Fitz]

Try removing the battery and shorting those two pins together for a moment like Harvey suggested.

I tried that too...grr. Thanks a bunch for all the help so far.

 

[lenjack]

There are probably several fan headers on the board, and only one is labeled cpu/heatsink fan. If you have it plugged in to one of the other headers, you can't boot because the board thinks you have no heatsink on the cpu.

 

[VirtualLarry]

There are probably several fan headers on the board, and only one is labeled cpu/heatsink fan. If you have it plugged in to one of the other headers, you can't boot because the board thinks you have no heatsink on the cpu.

This. Make sure that there is an active fan plugged into the CPU fan header, with an RPM sensor wire present. Otherwise, it will boot, but immediately shut off.

 

[A Casual Fitz]

UPDATE

So I purchased a new CPU and a new PSU and got the same results both times. To Lenjack, yes I checked on the manual for my motherboard to make sure that it was in the right slot. What does this leave me with now? Dead motherboard?

 

[Matt1970]

Unplug everything including add-on cards and ram and processor. Now just try to run it with just ram, processor and video. If it runs, then try plugging one thing at a time back and testing it.