thats really weird behavior. Did you try to stresstest your PC with Prime95 and Furmark? Does it restart when you run them?
What does the eventviewer show after this happens? Have you been able to check out the logs?
Stress tests, gaming sessions for hours, stable as rock.
I suspect it's the hardware acceleration in chrome. Disabled it a week ago and now I'm waiting with the PC up 24/7 and used for heavy gaming sessions etc, just like before.
So far so good.