Asus uses Intel's 6702PHX workstation/server Southbridge...
...that supports two PCI-X slots.
This jumper defines the PCI-X bus speed (Auto/100/133 MHz). It reaches 1.06 GB/s at the maximum speed using its 64-bit bus width, but the bandwidth is shared by the two slots.
A Marvell 88SE6141 PCI Express SATA controller offers four additional ports for hard drives.
The dual Gigabit Ethernet controller is attached via PCI-X.
Asus provides an 8-phase voltage regulator for maximum system stability.