If you click on display signature in your profile it will display your sig to the forums, I see possibly your first problem, you list 6G of Corsair Dominator, did you purchase a 6G kit = 3 x 2G modules?
And do you have all three modules running in your present setup?
If the answer to that is yes, you need to either buy an additional 2G module and run in dual channel mode again, or remove one of the 2G modules thats causing you not to be able to run in dual channel mode.
What operating system?