can we use two different rams

fx 4100 quad core processor 3.60 ghz?

RAM: 2GB-DDR3

MotherBoard:GIGABYTE 78LMT-S2


 
Can U suggest me a graphic card


 
Resolution-1366*768
fx 4100 quad core processor 3.60 ghz?

RAM: 6GB-DDR3

MotherBoard:GIGABYTE 78LMT-S2