the ram is built into the gpu. the newer gpu will have 2g or 4g of ram. the larger cards are better but more costly the more ram on the gpu the more the card frame buffer in a game.
with newer cpu not gpu the faster the ram on a gaming rig the better but be care full at some point with ram your going to be over paying for it for very little speed gain. if your looking for parts for a full rig. if you can wait till the end of the year intel dropping newer brodwell cpu and mb with newer ddr-4 ram. be care full right now on intel build. intel dropping newer 9x chipsets and a small haswell refresh then the newer brodwell and haswell-e cpu are dropping after june.