TERA has crashed multiple times giving a BSOD. This does not happen with any other games so I know it's not the cards I have running atm. I've noticed though if I use the Pre-Defined Crossfire Profiles it will no longer crash (APB worked great) but selecting which one needs to be done carefully. Extremely old ones (Gears of War) will no solve the issue where as Mass Effect 3's will cause the game to flicker a ton. I'm trying to figure out what is the top 5 newest games on this list that Crossfire has a profile for. I know Mass Effect 3 and Batman (flickers as well) are the newest. What are the last 3 and maybe this game can be playable. If I find out before this is answered then I'll edit this post.
Mass Effect 3
That is what I got so far just off that has a profile. Striked thru doesn't work for TERA.
So APB seems to be what's best for now. Sanctum gives a better FPS but less stability. Any games created and supported before June 29th I'll test.
This appears to be a gaming post. Try posting it in the AMD gaming forum here: http://forums.amd.com/game/
Hopefully, you'll get a better response to your gaming questions over there than here in the software developers forum.