try using the vsync and force frame limiting options in the video options panel for the game.

set vsync to on, and force the frame rate to something below 60. I use 50 for mine, and that fixed all the problems with heat generation.

for a game like this, that isn't a FPS, you don't need high framerates. even 30 might be good enough for some, though that low does tend to bother my eyes a bit.