I just wanted to start this is a thanks for all the help this site and it's community have given me. You guys are awesome.
I recently all but completely rebuilt my computer with a new PSU, motherboard, CPU, Case and RAM, and all was well with the world for about two months. Then just within the last week or so this has cropped up.
I'm running into an issue where my computer restarts at random. When it happens the screen will go black and then the computer will reboot and load normally. This happens both when at load, for instance running a resource intensive game, or when just watching netflix or browsing the internet. The restarts are very intermittent and can go for days without happening or will happen back to back.
I've run prime95 for over an hour with no issues, so I don't think it's the CPU. I've run furmark and kombuster tests, and there have been no issues. Neither the CPU or the GPU are anywhere near overheating at load, the CPU is at roughly 55C and the GPU around 68 to 70C during the tests rather steadily. I've also run Memtest86+ for over two hours with no errors, and run checks on both of my hard drives just for good measure to no avail. There were no errors there either. The problem has persisted through a fresh install of windows on a freshly partitioned hard drive, so it does seem likely to be hardware, and not software.
That pretty much leaves me with my power supply or my motherboard as the culprit, as far as I can tell. I'm running out tomorrow to get a power supply tester, but until I get it was was hoping someone might have a suggestion of something I missed or have a similar situation that might shed some light on the issue.
Intel Core i5-3570K Ivy Bridge 3.4GHz
ASRock Z77 Pro3 LGA 1155 Intel Z77
Antec High Current Gamer Series HCG-750 750W
ZOTAC AMP! ZT-50302-10M GeForce GTX 560 Ti
Crucial Ballistix sport 8GB (2 x 4GB)
Windows 7 Home Premium (64)
Did you check windows Event viewer?
Sometimes blue screens are set to be very hard to see when they happen.
If you have no errors in your event viewer except for "the system shutdown suddenly", then more than likely it's a hardware issue with the mobo and psu being culprit.