What are your CPU temps like when you're playing?
I watched my friend play on his 6600k with a Titan X, and it looked like he was experiencing some serious thermal throttling (bad airflow in his case).
Your graphics card only has 3 gigabytes of VRAM (compared to a standard gtx 970 that usually has 4 gigs). Also your CPU is running at 2.7 ghz, whats the turbo speed?
Sounds like your CPU may be getting too hot and forcing your computer to shut down via the safety settings, you should download a program to check your CPU temps