I am not sure that a dual core (in my example case, AMD) on AM3 socket will be a bottleneck since it's new gen. Nothing to do with x2 or x4 but more the fact if the generation of your card is the same as the cpu generation. If I use a CPU from 2005 with a vgx of 2009 it is logic that it will slow down and that's not because I got a x2 or a x4. There are other factors like the FSB speed... Correct me if I am wrong but I think that this sounds more correct