iirc, AMD CPU has no 3rd gen pci-e support yet so you are running at pci-e 2.0. I would want mine to run at 16x both cards and deal with the heat (Kepler is not the hottest card compared to previous generations) in another way with fans and/or watercooling. Probably not the answer you were looking for, but I think the speed of the cards outweighs the heat for me.
I received my HAF XB from the CM store yesterday. I will post pics once it is filled with my goodies and ask to be admitted to the fine club here.
Edited by vaporizer - 5/10/13 at 2:34pm