System restarts during gaming

[Cosset]

I have a gaming PC that restarts during gaming. This has been happening ever since I started to use this system again a few weeks ago. I can actually reproduce this like clockwork with OCCT by running the GPU:3D test. Shader complexity turned all the way up to 7. After starting the test it will run up to 30 seconds and then restart the PC. I logged the GPU specs and I have posted them below. At this point in time I think the issue is either the graphics card or PSU. But how can I determine which one to replace. I don't see any temps out of range. The highest the GPU got during the test was 67. I would welcome any ideas at this point in time. Thank you!

PC Specs:
Intel I5 2500k - not overclocked, never has been
MSI GTX 550 Ti Hawk - Factory overclocked
8GB Gskill Memory
ASrock Fatality Performance P67 motherboard
750w Thermaltake PSU
CD/DVDR/RW
Caviar Black 1TB HDD

GPU Specs right at restart:
GPU Core Clock [MHz] - 950.2
GPU Memory Clock [MHz] - 1050
GPU Shader Clock [MHz] - 1900
GPU Temperature [°C] - 63
Fan Speed (%) [%] - 93
Fan Speed (RPM) [RPM] - 4320
Memory Used [MB] - 151
GPU Load [%] - 26
Memory Controller Load [%] - 7
Video Engine Load [%] - 0
VDDC [V] - 1.0750

[Remilia]

Abrupt shut downs without a BSOD from what I've seen is usually the PSU.

GPU temp is fine but that fan is going on roids.

[katmandu26]

You didn't mention the OS. Are you running on Windows 10? It never shut down on me until I updated to 10, now it does it pretty consistently while running WoW. Once I turned down some of the more CPU intensive settings (view distance, flora, shadows) it stopped happening.

[wregelmann]

Hey Cosset, have you checked the CPU temps also? You didn't mention a fan/heatsink, so I assume you're using the stock one that came with your i5-2500k. If possible, run a program like CoreTemp (http://www.alcpu.com/CoreTemp/) and read the temperature while the game is running. At >90C, an overheated processor can cause similar behavior to what you're describing.

[Cosset]

Oh the heatsink is a Scythe Mugen 3. It's the size of a small house lol. Sorry forgot that one. It is running Windows 10 but this was happening since before I upgraded. Ran a CPU test in OCCT and the following was the max obviously 100% CPU usage. Let me know what you all think. Thanks for your time.

Sensor - MAX
CPUTIN - 44c
Core #0 - 51c
Core #1 - 57c
Core #2 - 59c
Core #3 - 57c

- - - Updated - - -

Also just to take it out of the equation I disabled the bios protection for overheating just to see if it would go away and no dice. It only does it when I'm doing very graphical things. I have my wow settings turned down too. I am running a 1920x1080 resolution on the display. Thanks again!