Hey all,
Recently I got my hands on a HD7950 card which I decided to crossfire with my existing 7970.
I have some major issues with Crossfire enabled, where the game chops down to unplayable stutter when I run the game with crossfire enabled. If I turn crossfire off, it works perfectly and the stutter is gone. I tested this by standing in orgrimmar where I had ~50fps and smooth play on a single card, and enabling crossfire wrecks the performance to an unplayable stutter at ~10-15fps. The problem appears to be limited to WoW, as I've tested Crysis, Crysis 2 and BF3 where in all 3 I get great crossfire scaling.
What I'm running:
-Fresh install of Windows 8 & the latest AMD Beta driver 12.11
-The game in full screen, tested both 32 & 64 bit clients
-Core i7 2600K @ 4ghz
-16gb RAM
-Gigabyte GA-Z68XP-UD3
-850W Corsair PSU
-Both cards at stock clocks
-The cards: Powercolor HD7970 reference design + XFX HD7950 Double dissipation
Some things I have tested to no avail:
-Swapping the crossfire bridge
-Fiddling with crossfire profiles (AFR Friendly, changing to another game's profile, etc...)
-Tested both cards standalone and had no problems with either one
I'm starting to run out of options here. I'm guessing it could be:
-Win8 compatibility issues
-12.11 beta driver has a problem with crossfire (I will try going back to 12.10 WHQL today after work)
-Would be strange though, because other games run and scale fine
-There is some unforeseen compatibility issue
-The unusual 7970+7950 crossfire setup is the problem, again strange because other games run fine
Anyway - if you guys got any ideas I'll gladly listen and take any suggestions. Obviously there's not a whole lot of need to run WoW with a crossfire setup, but it would have been nice to get it working since I do have both of the cards :-)