290x in crossfire here. After trying drivers 15.6, 15.7 and 15.7.1, I am forced to tell AMD fix their mess!
15.6 suffer from flickering, 15.7 and 15.7.1 suffer from huge FPS drops in crossfire.
FPS average with 15.6, 48 FPS
FPS average with 15.7 and 15.7.1, 29 FPS
FPS average with one card: 24 FPS
Setting: 2160p, everything at ultra except AA and Hairwork disabled.