My motherboard Asus P5QL-EM supports up to 8GB of RAM ( at least that's what it says in the manual). I currently have DDR2 , 2 X 2 GB (= 4GB) of RAM installed. However when I tried to install 4 GB more ( 2 x 2 GB) then the system did not support it. Is there a special kind of RAM that need to buy so that it can go along with my already existing 4GB RAM? Any help would be appreciated. Thank you.