my board is this Intel® Desktop Board DH55PJ
it has 2 slot for ram, currently i'am using 1 (corsair 2gbddr3 pc 1333) i'm planing to make it 4gb.
my question is can i just buy another 2gb ram to make it 4gb or i have to buy a single 4gb ram. or do i necesarily need to fill the two slot of my motherboard. need help im quite a newbie my friend say my ram bottleneck my gpu and cpu need advice THANKS!!!!!!