RAM mixing amounts

Legolover16

Honorable
Oct 5, 2013
17
0
10,510
I currently have 4gb of ddr3 1333mhz ram installed in my ga78lmt, and I am adding a 3rd 1280x1024 monitor to my system. I would like to upgrade the ram, but an extra 4gb is a bit expensive in the uk. Could I add an extra 2gb to give me a total of 6gb, or do the ram modules have to be the same?

I don't know if this would make any difference but I have a phenom ii x4 965BE and a sapphire hd 7850