New Computer = Burning In Hell

[Dem Pyros]

I just built my new computer, 2 gigs of ram, EVGA 680i mobo, E6600 Core 2 Duo processor, 700w PSU, 8800GTS, etc. etc.

Well i finally turn it on and YAY! IT BOOTS!

So i go get a soda, come back 5 minutes, and the system is off. Quick "WTF?" and i boot it, go into the bios, and look at the temps. Sure enough, the CPU is at 55 C and rising about 2 C per second. So after a minute or two, the processor peaks at about 90 degrees and the computer immediately shuts down.

Everything else is fine (Chipset around 35, board at a cool 27), all the fans are spinning, even the processor's heatsink fan.

So here's the question:
What is wrong? Do i need a new heatsink? Buy more/reapply thermal paste?

Before you ask, the heatsink IS touching the processor.

[onelegout]

you only need a very small amount of thermal paste - the smaller the better. Ensure that your heatsink is applying significant pressure onto your processor, don't just have it sitting on top as this will not work. Ensure that your heatsink's fan is working, etc.
Run it on its side with the side of the case off. and look for anything going wrong.
H

[Dem Pyros]

I Re-mounted the heatsink with some info from other boards and now it's working fine, thanks.