How long was it running before it shut off?
Was the fan running?
I'm guessing it over heated, but with out more information, hard to say.
Can you tell us what the temps inside the case got up to?
Maybe you don't have a big enough power supply to run it and it starved for power.
What size power supply do you have?
Could be the drivers,
EDIT: Just saw your specs in your sig.
600 watts should be enough.