FWIW, I thought that the following comment from an article on PCI Express architecture at the Tom's Hardware site(http://www6.tomshardware.com/graphic...310/index.html) provides a good explanation as to why 8X AGP currently provides no distinct performance advantage over 4X AGP wrt gaming:

"The reason why there isn't more of a performance payoff is simple. Games are designed in such a way that they don't send more data to the graphics card than the AGP bus can handle. Otherwise, there would be noticeable stuttering in games.
On top of that, the amount of memory found on modern graphics cards (up to 256MB) makes it completely unnecessary to page out data such as textures to the system memory via AGP."