I'm currently using Diablo. The f argument worked great, thanks ssateneth.
Any reason why you'd want to do that? You bought the most expensive card, I say let it bleed.
Summer is quickly approaching, and I won't be mining if it means turning the AC up too far, as I'll spend more money cooling the room than I'll make.
You're not making any sense. All heat produced by the computer (and video card) has to be removed by the A/C, regardless of how little or much it's making. Since the computer produces a certain amount regardless of how hard the card is worked, you're effectively making it less efficient to mine by doing this (although it will cost less obviously).
It would make more sense to mine when it's cool, like about midnight to 8am, since the A/C will have to work less hard.
The best solution would be to stick the computer in an un-A/C space, and fan it like crazy, since fans take way less energy.
The next best solution is to vent the computer outside; any air vented outside will be replaced by outside air (somewhere in the house) and since air from outside is very likely cooler than the computer's heat, it still makes sense.