Firstly, congratulations on equipping your PC with the most powerful dual GPU configuration out there in the market today.
Don't worry about your PSU (I was running my CrossFire 7970s on a 750W no problems before) and don't worry about disabling ULPS unless you are overclocking.
My advice: ensure you are running latest drivers. I have been using 12.11Beta11 drivers available on the AMD Catalyst driver page for a month and those are the best yet for both stability and performance. Try cleaning the old drivers also before installing the latest drivers. Finally some older games just won't play nice with CrossFire so as suggested disable CrossFire in such scenerios.