You will need some serious airflow in that case. I got 2 FE cards in right now. Top ones sits at 80c 100% fan while the bottom card gets around 70c with 80% fan under 24/7 load. Its a little better with a none blower cards, but than you really need to find a way to dump the air. If you are just playing games, I don't see a problem. However the top card is going to be upwards of 10c over the bottom card. Heat raises.