PCI-X
From OCAU Wiki
This is a variant of the normal PCI slot, but it is only seen on server/workstation mainboards. Although the slots differ in length. PCI cards (except early cards) will work in a PCI-X slot, although only at the PCI bus' specified speed (33/66Mhz).
Compared to PCI:
- PCI-X changes the protocol a little and increases the data rate to 133MHz
- PCI-X 2.0 uses a 266MHz rate and also a 533MHz rate, expands the configuration space to 4KB, adds a 16-bit bus variant and allows for 1.5V signalling.