I have a G5 with 8 gigs of ram, but it does not make a huge difference when playing games. It really shines when running big programs and multitasking. I know a guy that has 4 G5s linked together as some kind of supercomputer, but i'm not shure if it would make much difference for gaming. Those monsters are usually dedicated to a work function. I'm thinking that if that guy does have a 13 giger, that he cannot utilise all of it for a single program.