Current OS: Win 8.1 Pro x64 For the past few weeks, I had been having issues with my computer with black screens only during gaming. At first, it seemed like a power issue since the machine kept shutting off and rebooting with no BSOD or error codes. So I got a new PSU. Still kept happening - tested each GPU individually and all passed without error/problems. Black screen problem still persisted. So I installed Win 7 x64 on a spare HDD and checked to see if it was software/drivers - still got black screen/reboot. Decided it had to be the motherboard - RMA'd the board and just got a replacement (2 days ago). Still get black screen/reboots. Reflashed the GPU BIOS - worked for a while when the voltage was left at stock (instead of 1.212V). However, still got black screen/reboot after about an hour. I decided to test RAM w/ MemTest86+. Tested RAM @ XMP setting (Corsair Dominator Platinum 32GB 9-11-11-31 @ 1.65V) - got a ton of errors in MemTest86+ (411 errors after about 8.5 hours). Reset RAM to "Auto" (1333Mhz) tested again - no errors so I booted into Windows. Tried playing AC4 and got black screen + reboot within 10 minutes. Tested each RAM stick individually today and 3 of them passed fine with no errors while the fourth one had errors in the first and second passes - 10 errors. Took two sticks out and put two "good" sticks of RAM back and fired up the computer. Booted into Windows and ran Heaven 4.0 & Valley - both passed without issue with the GPUs OC'd and overvolted @ 1.212V. Thought I had solved it. Fired up AC4 and got a black screen in about 10 minutes. Tried different GPU settings (stock, lower OC, no over-volt etc.) to no avail - all gave black screens within 20 minutes (some sooner). Tried BF4, got a DirectX error - game wouldn't even start! Tried several times - nothing! Tried BF3, got a black screen within 3 minutes. My PSU connected via a thick 12AWG cable to a 20A breaker. The PSU cable (PSU: Lepa G1600) itself is quite think (albeit short). I have NO idea why this is happening - I have either tested or replaced everything. There are no error codes; just a bunch of Event ID 41 in Event Viewer but that doesn't indicate anything useful (just unexpected crash/reboot). Really need help with this - I having been banging my head against a wall for about a month now with no luck on this issue!