Actually Crossfire works perfectly in AFR compatible and 1x1 modes with following settings:
- Turn off TXAA
- Turn off PostProcessing
- Tone down Special Effects
- Tone down Shadows Quality
First three are obvious as they use previous frames to anti-alias, blur, etc. so they need a lot of transfers between cards as they render alternate frames. No idea why shadows affect Crossfire though. Anyway, with above settings one can get high and smooth framerates in Crossfire configurations.
I also noticed that VSR doesn't work - selecting resolution higher than native doesn't switch screenmode at all.
Why do I bother though, devs don't seem to read these forums anymore...