PCI-X
![](/Images/godic/202502/01/Intelpromtserverpcixadapter1000mta3424625.jpg")
![Dual Port Network Card for Single PCI-X slot to save on PCI-X slots and use the full potential of the PCI-X 64-bit bus](/Images/godic/202502/01/Dualportintelmtpro1000mtserveradapterspc4625.jpg")
![3.3 V and 5 V keying of 64-bit PCI cards (both PCI and PCI-X). While most 64-bit PCI-X slots are 5 V and are backward compatible with common 32-bit 5 V PCI cards, a number of 64-bit PCI-X slots are 3.3 V and will not accept 5 V cards, by far the most common voltage for 32-bit PCI cards.](/Images/godic/202502/01/PCI_Keying.svg4625.png")
PCI-X, short for Peripheral Component Interconnect eXtended, is a computer bus and expansion card standard that enhances the 32-bit PCI local bus for higher bandwidth demanded mostly by servers and workstations. It is a double-wide version of PCI, running at up to four times the clock speed, but is otherwise similar in electrical implementation and uses the same protocol.