OK so I played res5 and activity on the second gpu i could catch at like 3% somtimes switcing back and fourth plus it heats up so I'd say its working, nest thing is I turned vsync on and my first gpu went form 98% to like 27% activity. My next question is if vsync takes my fps from like 200 to 300 down to 60 whats the point of crossfire? 1 of my 5870's blows that away?
Obviously, for this particular game, you have no use for crossfire. Your monitor only displays 60 FPS even if your video card is generating more. V-sync forces the card to only display at most 1 frame per refresh of the monitor.
However, with higher resolutions and more demanding games, you will likely have a use for it.
BTW, what resolution do you play at?