DNF Turns Off Monitor - Gfx?

I am aware of the fact that my current gfx cards may be low end for DNF (Radeon 5750x2) but what is happening is that the game shuts down the monitor ingame. Like shutting down the signal (?). This occurs anytime from 5 minutes in to the game up to 30 minutes or so.
Only solution to get signal back is a hard reset.I have set up a GPU monitoring software (AMD Overdrive) to measure temps and will post logs here later, my intention with this post is to figure out any other verification measure I might take to verify that this is indeed this game overloading gfx cards?