APU should honestly be ran with DDR3-2133 or DDR3-2400, not DDR3-1600. Even in Dual Channel mode, that's a MASSIVE difference in bandwidth for an APU, the graphics portion NEEDS that extra bandwidth, CPU not so much.
As for the motherboard, get one that lets you set the amount of memory, not the most generic of generics. Hell, even my mothers HP Desktop dedicates 25% of total system RAM to the graphics chip on an APU, 2GB dedicated out of 8GB, makes for a fairly decent little machine. Granted I have never gamed on it or attempted to.
But please, for the love of god, even if AMD isn't all that great, at least give it a flipping fighting chance with a decent board and RAM.