Air or liquid cooling? What thermal profile did you select under the Alienware Control Center? Do any of the fans become loud when playing games? You can read the temperature in Alienware Control Center (AWCC for short), together with fan speed for intake and exhaust fan. I am thinking you have thermal problems, since it seems to be working fine the first hour or so. 
Hey folks. So far the Aurora R10 is amazing!!!! However, I've noticed that every now and again, after playing a game for about an hour or so the frame rate will suddenly drop to what looks like 5 frames per second and looks to be struggling. Not sure what's happening. Any ideas?
Aurora R10, periodic massive FPS drop