I actually had a mobo that did the same thing, I was getting random reboots and shutdowns, then got no video signal, RMA'd the board and haven't had the problem since. It's the board in my sig. If it can still post I'd see if there's a BIOS update availble.
EVGA 680i SLi
E6400 @ 3.0 GHz
4 GB OCZ Platinum Rev. 2 EL @ 880
400GB + 250GB Seagate Barracuda SATA2
Antec P180B Case