System Turning Off Problem

[Duque]

So I just built this computer with i7 920, asus p6t deluxe v2, and sli 285s running windows 7. This is the second time that the computer seems to shut down by itself. The screen goes black and my monitor begins to cycle through modes again, but the computer fans stay on. Other than that, I get no response from mouse or keyboard and have to manually turn off and back on. This is my first build, so I have no idea what the problem is. Is this a Windows 7 issue or something else? Any help is appreciated. Thanks.

 

[Proximon]

You'll really need to be a bit clearer.

http://www.tomshardware.com/forum/264823-31-progess-troubleshooting

"This is the second time that the computer seems to shut down by itself" - What does that mean? It has shut down on it's own twice since you built it?
How long has it been? You built it today? Last week? "Just built" means different things to different people.

How about the rest of the parts list?

 

[Duque]

built last week. 2 wd t tb drives, samsung t240 monitor, cosmos 1000 case, sli 285s, 6 gb ocz plats, i7 920 w/ noctua cpu cooler, and asus p6t deluxe v2. Im not sure what to call it because it doesnt fully shut off. It is totally unprovoked. Happened once in a game, and once not. The monitor goes black and then recyclyes like its looking for a signal but none comes. The cases stays on (lights, fans, etc), but its impossible to access the computer via mouse or keyboard. I have to manually turn off.

 

[Proximon]

This is called a hard lock. The fact that you loose video signal may be important, or may not.

You still have not listed your PSU.

You should remove one GTX 285 and see if it happens again.

 

[Duque]

corsair 850

 

[shortstuff_mt]

This could also be a RAM problem. Have you manually set the RAM speed/timings/voltage to the manufacturers specs in the BIOS? Have you run Memtest86+ overnight to test for RAM errors?