Hi, i have 2 sticks of 2gb DDR3, and i want more, should i get 1 stick of 2gb, or 1 of 4gb. The mainboard is an ASUS P7H55D-M PRO. Also im not sure about the speed and voltage, i think is 1333, but im not sure.
http://i.imgur.com/BOeHC7h.jpg
http://i.imgur.com/eeCvmkF.jpg
http://i.imgur.com/BOeHC7h.jpg
http://i.imgur.com/eeCvmkF.jpg