What are you using to monitor FPS? I have MSI AB but I cant display FPS or GPU usage while in game. That said, I've switched between CFX and Single card for ENB mods and the difference is at times marginal in game play. Like others have said its just terribly optimized for CFX. FIngers crossed the July 31st CFX update includes Skyrim.
Edited by Spin Cykle - 7/23/13 at 6:00pm