Either your cards are running way too hot, or you overclocked them a bit too much so after a while, GPU Driver crashes.
Hey Guys!
I'm using these settings
-tt -30 -cclock 1150 -mclock 2150 -cvddc 875 -mvddc 875 -dcri 6
Should I lower anything?
Definitely lower your memclock and coreclock a bit, 1075-1100 coreclock with about 1600 memclock, if it is stable, you can increase later.