I'm just adding to this to maybe help people out.
I'm running a Ga-990FXA-UD5 with a FX 8150 cpu and the memory is Mushkin Redline PC3-12800 with timings 7-7-7-18.
I had to do what somebody else posted on this thread that to get it to work I hard to set the speed & timing manually.
Memory speed set to 8.00 / 1600
Timings set to 7t - 7t - 7t -18t