I'm a bit late on this thread, but I thought I'd add my bit for reference if anyones looking @ backdated help, as well as to increase my post stats
Please, anyone correct me if I'm wrong - I'm working from memory here.
AGP details:
8x = AGP 3.0 supports 1.5v cards.
4x = AGP 2.0 supports 1.5v/3.3v cards.
2x = AGP 1.0 supports 3.3v cards.
Some 8x boards now support 3.3v 4x AGP. As far as I'm aware, you cannot use 2x AGP - THIS WILL DAMAGE THE PORT.
There are also AGP PRO 2.0 ports - lets not get in to that LOL
Also, just FYI:
PCI ports transfer data at a rate of 33MHz.
AGP transfers at 66MHz.
Therefore 8x66MHz = 528Mhz, so thats where the main advantage of AGP graphics over PCI comes in.