With two cards, if you're getting a lot of heat from the PS and no heat from the other exhaust fan then the heat you're feeling coming out of the PS could actually be FROM the PS.

Do you know the quality of the PS?  Is it a "cheapie" or something more premium?  I ask because cheap power supplies have pretty sucky efficiency ratings, so the more power your system needs to more heat your PS generates.  It you're using a budget PS I'd definitely consider upgrading to a more premium PS with dual fans and/or "80 PLUS Certified" at least (80 PLUS Gold/Platinum is better, but more expensive).