support higher clock speeds (up to 133 MHz), but is otherwise similar in electrical implementation. PCI-X 2.0 added speeds up to 533 MHz, with a reduction in electrical signal levels.

The slot is physically a 3.3 V PCI slot, with the same size, location and pin assignments. The electrical specifications are compatible, but stricter. However, while most conventional PCI slots are the 85 mm long 32-bit version, most PCI-X devices use the 130 mm long 64-bit slot, to the point that