Hey Same setup crossfire 270's mantle gives terrible performance change to dx11 and then set ultra then make sure game is fullscreen Crossfire Does not work if not in full screen! had to make that clear I had the same problem until I found that out afterwards 80 fps
It is in full screen and I am still getting around 30-40fps on ultra 1080p
Do you happen to be using mantle I have been experimenting with mantle vs directx and I get 40 or so fps on mantle which is annoying as **bleep** but put it on direct x and 80fps
Also make sure that v-sync is disabled for crossfire because this causes microstuttering and might cause the fps to drop
