|Buying 8Gbs now and 8Gbs later might not be tbe the best idea.|
To get the best from dual channel you need matched pairs. Although you may have two sets of RAM with the same specifications there may be slight variation in their timing, while not significant on their own, can make a difference with the tight timing that is needed in dual channel mode.
With matched pairs, the individual timings will be matched exactly for maximum performance. 2 x 4 now and another 2 x 4 later would be a better plan. The motherboard will support it.
message edited by StuartS