Do you mean PCI-Express graphics cards?. I've never heard of a PCI-X
graphics card, there really isn't any reason for it to exist. PCI-X is the
last incarnation of the parallel PCI bus. The basic PCI bus is
32MHz/32bits. PCI-X is 100-133MHz/66bits. It's used in servers only. There
are a limited number of cards available for PCI-X, mostly things like
Fibre channel controllers. PCI-Express is the new serial interconnect.
Each link is 2.5GHz (2Gbits because of 8B/10B encoding). PCI-Express can
have from 1 to 32 links per connection so it's capable of much higher
performance than PCI-X or AGP. Next generation systems are going to
replace both the PCI bus and the AGP bus with PCI-Express, but those
boards aren't out yet. For now what you want is AGP-8X for graphics, most
of the 940 boards have AGP-8X support. If you want PCI-Express graphics
you will have to wait another 6 months or so but it's not worth it.
Chances are there won't be any performance difference between first
generation PCI-Express graphics cards and their AGP-8X contemporaries.



Pci-X is still developing however.. (I dont understand why, unless there is
more reliability there)..
you can get SATA Pci-X cards .. the PCI-Express stuff will happen with
the Nforce 4 chipsets (or so I hear) .. I have seen some VIA roadmaps
showing the 800pro having express support (but it doesnt show it now) so I
am guessing they have push'd it back for their 900 series.. This is
something I want too, but I want to see some of the express spec (right now
it's somewhat limited as to what I can open and read on the psig site)