They're running different nVidia northbridges.
The A7N8X (and the deluxe) run the nforce2 ultra 400 chipset.
The A7N8X-X runs the nforce2 400 chipset.
The Ultra supports dual channel, while the non ultra doesn't. The actual performance difference is minimal, I think there was a review on Anandtech that showed the non ultra actually outperformed the ultra on several game benchies.
The A7N8X (and the deluxe) run the nforce2 ultra 400 chipset.
The A7N8X-X runs the nforce2 400 chipset.
The Ultra supports dual channel, while the non ultra doesn't. The actual performance difference is minimal, I think there was a review on Anandtech that showed the non ultra actually outperformed the ultra on several game benchies.