One more thing...
I'm in mountain time us so when I first wrote that it was hastey and non-informative (was half awake at the time.) I did do a little bit of changes to get crossfire to work correctly. I ran it as etqw.exe to remove the throttling thing and to run the correct profile of crossfire (there's like 3 different modes crossfire can run in *scissoring, alternate frame, and supertiling.*) I highly recommend that you run the fans at 55% or so especially if you are using a board like the intel x48 where the 2 4870's are right next to each other. I am really interested to see if trifire or quadfire work with furmark running the etqw.exe profile.