CSGO + Win8.1 + GTX 780 ti = PC Shutdown

[benniS]

Hello guys,
a few days ago i got my new PC with the following specs:

CPU: Intel Xeon e5-1620v2
RAM: 16GB
GPU: PNY GTX 780 ti XLR8 OC
Windows 8.1 Pro 64bit
PSU: 800W
Monitor: LG 29EB73-p (21:9 Resolution(2560x1080))

and now my Problem, after going in a game i can play for about 20sec, after that my PC just shuts down and reboots, no BSOD or anything, just like there would be no power anymore. When i run the Unigine Heaven Benchmark the GPU goes all the way up to its full power and everything runs good, so i guess the problem istn't the GPU or the PSU.
I would really appreciate it if you guys could help me because i really want to play CSGO again.

LG Creepy

[oldirty`]

Sounds like its getting too hot, but then it should shut down with the benchmark too.
Download SpeedFan and check it, its worth a try.

[benniS]

I already got GPU-Z, the GPU never goes above 70celcius. The Fan speeds are also good, around 1500rpm.

[Daddy Shark]

Did you build this rig yourself or did you buy it pre-assembled with windows already installed?

[oldirty`]

And the CPU?

[benniS]

I got it pre-assembled.

[benniS]

The CPU stays at 63celcius under heavy load.

[Daddy Shark]

The first thing I would do is install the updated drivers for your motherboard components and the video card.

Mobo drivers here https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=20775
Video card drivers here http://www.geforce.com/drivers/results/80913

Check your CPU temps at full load as well. Report back what you find. Nevermind, your temps are good.

[๖ۣۜC𝖆𝖘𝖆𝖜𝖎]

Drivers, software, virus.
Something of these 3 is causing your issue 100%.

[oldirty`]

Thats a weird problem. Usually its the cpu getting too hot when the system just shuts instantly down to prevent damage. You should probably contact the support from where you bought it.

[benniS]

I checked my Drivers they are all up-to-date. I read somewhere that it could be a problem with the source engine, but i don't believe that because gmod runs fine.