To keep this short and sweet, here are the facts:
I built the computer in my signature on February 18th and had to RMA two XFX HD7970 Black Edition cards on February 19th because of artifacting, tearing and pretty much every other indicator of back video cards. So yesterday, I get my new MSI HD7970OC cards and they work fine for about two hours of BF3 and Crysis 3. After the second hour, BF3 hard locks and I restart the system, angered because this is the same way the XFX cards behaved, minus the artifacting. So I restart, go into Crysis and 10 minutes later, BAM same thing.
I ran each card separately before setting up the crossfire, so I am very hesitant to believe I got two more bad cards from a different manufacturer. I have run Prime95 for 10 hours, Memtest86+ (new version) for about 7 hours and a 50-pass run of IBT, all of which pass with no errors.
So does it appear as if the motherboard is bad, since there are no CPU/memory errors upon conclusion of tests but all 3d applications fail at some point? I got the cards from micro center, so I can drive up there and return them, but I am just very skeptical to point my finger at the video cards at this point.