Originally Posted by l33tGaMeR
May be the brand difference... Asus and XFX may be causing an issue... Some brands set their cards so they only crossfire with the same brand...
Well the only difference between the XFX and the Asus us the Bios, all 5870 avaliable right now are BBA.
Flash the XFX with the Asus bios and the the problem might go away.
The Asus allows for higher driver level OC anyways.