Don't know if it has been noticed but since it is hard to distinguish windowed and full screen mode, it may happens that some of you are have windowed mode set up. It may result with micro-stutter also. I know because I had such situation. Switching to full screen solved the issue
Odd. I got the opposite effect when I had 2 cards. In many games (or maybe all?? not sure..) entering windowed mode disables crossfire, which in turn reduces microstutters as you are now back at using one card, but obviously will now have reduced fps aswell. What works for me might not work for you though, and vice versa, so everyone should try it
I've noticed that with some funky plugins (afterburner onscreen display) the videocard only being used 70%. thats a 5970 3gb at 1000mhz and 1250 ram
One of the hassles with multi card setups , you dont know if its the game thats having problems getting all cards to work fully, the drivers, a combo of both, or if you are simply just being CPU bound (held back by your cpu). Can you try switching to full screen mode? I believe alt+enter should switch between 2 or 3 different screen modes, sometimes things dont run as optimized in windowed mode. (my post above yours).
