Duct tape it.....
Not really, umm... is your motherboard atx or at power supplied? If it is at, then the psu may be bad.
If it is atx, then it may be the motherboard.
I do hope that your cpu is running at 100 degrees FARENHEIT, and not celcius.
One sure fire way to check to see what is wrong is to locate a freind that has a computer you can swap parts out with. It's tedious, but works every time.