impossible to run 2 x1800xt but what you can do if you think u can pull it off is flash to xl bios then manually edit to xt speeds/latencys...this is dangerous as u can flash your card badly, and you will void warranty, but if you flashed bioses on vga cards before maybe you can give it a try...your xts become xls to catalysts and then you will get crossfire tab in ccc