Yes of course. Mixed combinations work normal. Tested with 16.11.1 drivers, all works normal and good speed.
AsRock FM2+ BTC Board, Win7/x64 Ultimate, 6xGpuMod.
Sorry for offtopic, what board you recomend for FM2+ socket?
ASRock FM2A88X Extreme 6+ on my most recent builds, but I prefer to do 3 card builds (it's got a pair of 1x slots on it I don't use though).
I'm planning to wait for AM4 boards to start arriving retail before I even think about my next new buildup.