Computer Shuts down no warning

Hello,

My husband purchased his hardware from Tiger Direct two months ago and has built his own computer. Here are the computers specs:

Running Windows Vista
CPU: Intel E8400 776 chip
RAM: Corsair XMS2 DDR2 Model: CM2X2048-6400C4DHX [800Mhz, 4-4-4-12, 2.10 v] (times 4)
MOBO: EVGA 780I
HD: WESTERN DIGITAL WD5000AAKS (times 2)
GPU: BFG GTX 280 OC
SOUND CARD: SOUND BLASTER AUDIGY MODEL: SB0570
PSU: ULTRA X3 MODEL: ULT-HE1000X


He has two problems.. one he's pretty sure is a driver issue, he's occasionally getting a blue screen of death screaming about a driver problem (probably the new video card, no updates for the problem yet) The other problem is his computer will also randomly shut down. No warning, no blue screen and it doesn't restart. When he restarts it and checks his events log there is no indiciation that anything happened and it runs perfectly fine until the next time. It can sit for hours and do it... he could have it on ten minutes and it'll happen, he's been running a bunch of programs and he's been doing nothing at different times when this has happened. Every item in the computer is brand new... any ideas?