It's well known that using matched pairs of RAM in a single bank with Dual Channel Architecture is optimal, both so that the two sticks have similar timings, equal capacity, etc.
But what about between two banks?
I have a P8Z68-V (Gen3) motherboard, with 2x4GB in one channel. This leaves the second channel free. For optimal performance, should this be filled with another 2x4GB, or does it not matter, so long as the channel itself is balanced? i.e. could I stick in 2x8GB (to give a total of 24GB of RAM) and not suffer any performance issues/get the best performance?