Having the same issues, 15.12 I believe was the last driver that worked correctly.
1300 watt psu
Updated to 16.3 and I can say now that games will run in full screen mode with crossfire (I've had to add profiles manually as the scan option doesn't seem to grab all games) and all my previous DX9 and 11 games are working as expected. The only issue I see is that when Insurgency, I need to alt tab out and back for my FPS to boost back up. But I think this maybe related to the game.