We recently built a pc for work to do chief architect renderings. The components are 3930K, Asus X79 Sabertooth, (16 Gigs-4 Gigs Ea.) Corsair Vengeance LP, EVGA GTX 670 FTW, OCZ Vertex 3 SSD, Corsair H80i, and an Ultra 750w power supply. The pc is currently overclocked to 4.2 GHz via bios settings, XMP profile with everything on auto except CPU ratio = 42. The pc has passed 9 hours of prime 95 on small fft with no issues, CPU was hanging around 60C, the only thing that gets hot according to AI Suite is the "VCORE" which I'm assuming is the CPU PWM (not sure why they labeled it that way). The issue is that the PC will randomly lock up. When it locks up, some of the programs become unresponsive and some still work. The last time it locked up chief was completely locked but I could still jump between MS Excel and Outlook. After a while these programs would become unresponsive too. I could not access task manager and had to preform a hard reboot. Once I power the PC back on I am greeted by Overclocking Failed! I restart the PC and all is well for another week. I do not run to PC so it makes troubleshooting even harder. I have already taken the OC from 4.3 down to 4.2, tried manual voltage, and have lowered the RAM from 1600 down to 1333. I have also ran Memtest for a few minutes and all modules came up clean, however, I am planning to let it run overnight next week. I do have AI suite along with corsair link installed and do notice that AI suite produces weird readings from time to time such as mobo = -10C. Not sure if that has anything to do with it or not. Any advice would be greatly appreciated!