I want to upgrade the RAM in my system from 4gb to 8gb. I have 2 2gb sticks of OCZ AMD BE DDR3-1600. I'd like to get 2 new 4gb sticks instead of just adding 2 more identical sticks. If i'm not mistaken i'll lose my dual-channel by using all four dimm slots. So the question is what is the best 4gb module for my board?