Memory Issues

So I recently completed a build with the Asus sabertooth 990fx motherboard with the corsair vengeance memory 2x4gb 1600 (CMZ8GX3M2A1600C9B). I think that my problem lies with the memory somewhere. I have been trying to fix this thing for weeks with no solutions. Sometimes when I start the computer it only detect 1 stick of ram @1066 mhz (it is supposed to be at 1600) even though 2 sticks are installed. Other times it detects both sticks of ram at 800mhz. Whenever I try to manually change the DRAM settings, it will not boot, and I have to push the memok button. I have no idea what is going on but I would appreciate any help. Let me know if you need any info.

AMD fx-4170
Asus Sabertooth 990fx
Corsair Vengeance 2x4gb
2 Nvidia GTX 550 TI's
60gb solid state
150gb velociraptor hard drive