I've just got one of these and have fitted it and installed cat 12.8 drivers after removing nvidia. I tried guild wars2 and Diablo 3. Both caused a black screen and sound loops within 5 mins of playing.
I think I've sort of solved the issue by disabling the 5 entries for AMD hdmi sound that were added on driver install. I didn't have a lot of testing time, but managed to get gw2 in game and fast travel to lions arch. I also managed about 15 minutes in hitman sniper challenge.
Is there a better or proper fix? I'll be testing more after work tonight. I don't want to have the hassle of rma.