I went the crossfire route a few months back, but drivers and support were so weak, I dumped them (3870's). 3Dmark ran fine, but I had issues with every game I tried on it. What games, if any, do you run ? I was looking at the 4870's, but I just don't want to have to mess with a bunch of patches to get every game running.
The gaming experience with the 280 is fantastic ( and I remember saying the same thing when Diamond released the Viper550 !).
Bookmarks