Do not use Crossfire for mining, disable it.
Set the core clock to 1200MHz or lower (just enough to not affect your hashrate by a significant amount), as well as the voltage, and the memory clock as high as you can without getting any GPU Memory errors in HWinfo.
Look into BIOS modding as well, only through that will you have a shot at getting 30MH/s.
I did some bios modding and tuning is msiAB last day. HWinfo was running and showed 0 errors, but I saw glitches on the screen, and after a few mins my system froze. Tried multiple times with multiple variations but no errors in HWinfo, just glitches and crashes.
I did find the almost optimal settings, but HWinfo did not help me.
I think I missed something. Can you help me pls?