Markhavel: There is a bug in the game causing certain GPU to overheat, or more accurately, to use always use all GPU resources available. Either you computer is properly cooled and all this does is having the GPU fans spinning like there's no tomorrow, either space is more constricted in your computer and I guess the bios decides it's time to calm things done before damaging the computer and turns it off.
Unfortunately, there doesn't seem to be a fix in the work, notably because developers have a
hard time pinpointing this bug.
The latest build has been updated to Unity 4.2, perhaps with the Unity update the overheating problem is fixed?
