Everyone is right. DDR5 on a 128bit bus is like hooking a garden hose to a firetruck. If you will notice, the 9800GT is DDR3 memory on a 256bit bus. Which basically means that you get a higher bandwidth. Think of it as a highway, a 256bit memory bus is like an eight lane highway, whereas a 128bit bus is like a four lane highway. It doesn't do much good to have really fast memory if you don't have the bandwidth to let it scream.