Information to PCI, PCI-X and PCIe & PCI Express Slots

In the past years several additions and extansions to the standard PCI bus where developed. The PCI-X computer bus and expansion card standard was developed to increase the speed and is mainly used in server systems. Lately the PCIe & PCI Express was developed which is a serial bus system and also increases the speed. Modern Computer Systems may also offer slots for expansion cards supporting PCI, PCI-X and/or PCIe standard. None of them is compatible with the other.

PCIe slots look like the standard PCI slot and are usually shorter.

The following information is provided to shorten the path to the decision for the right expansion cards.

Today computer may ship with one or more of the following expansion slots:

• The "old" PCI Bus 32 Bit with 5 Volt.
   
• The PCI-X Bus 64 Bit with 3.3 Volt mainly found on server mainboards.
   
• The PCIe & PCI Express Bus (Peripheral Component Interconnect Express) is shipped with modern mainboards. The appendix x1, x4, x8 or x16 shows the number of Lanes and is a speed indicator (e.g. 250 MByte/s per Lane). Expansion cards with x1 fit into x1, x4, x8 or x16 slots. The slot x16 is mainly used by video and graphic cards.

The ones with the blue color are more widely used.

Please watch the position of the the notch(es) for proper orientation of the card.

Currently 32bit,5 Volt PCI slots are most common on desktop mainboard. PCI-X slots, 64bit, 3.3 Volt are common on server mainboard.

Universal PCI cards support two slot types: PCI and PCI-X.

PCIe slots (introduced in 2004) are becoming common on desktop and server mainboards.

All information provided herein without any warranty. Please consult the mainboard's manual for more information.