PCI Express

aliases:

• PCIe

One of the faster expansion bus types, one of the children of Peripheral-Component-Interconnect buses.

PCIe was developed to replace PCI, PCI-X, and the Accelerated Graphics Port (AGP). Instead of a shared bus, each PCIe slot links to a switch that prioritizes and routes data through a point-to-point dedicated connection. PCIe provides a serial, full-duplex method of transmission.

• PCIe uses several connection types.
  • PCIe types are defined by the number of transmission lanes that are used to transfer data.
  • PCIe defines x2, x4, x8, x16, and x32 connection types. For example:
    • PCIe x1 provides one lane for transmission (x1).
    • PCIe x16 provides sixteen lanes for transmission.
• PCIe data rates depend on the protocol version and number of transmission lanes:
  • 1.0: 250 MBps (x1); 4 GBps (x16)
  • 2.0: 500 MBps (x1); 8 GBps (x16)
  • 3.0: 1 GBps (x1); 16 GBps (x16)
  • 4.0: 2 GBps (x1); 32 GBps (x16)
• In addition to greatly increased speed, PCIe offers higher quality service.
• PCIe can run alongside legacy PCI technology (e.g., both PCIe and PCI buses can be in the same system).
• PCIe x1 slots are typically used for network cards, USB cards, and sound cards. PCIe x16 slots are primarily used for dedicated video cards.

PCIe cards are cross-size compatible when the slot size is the same or larger than the card size. For example, a PCIe x1 card can be installed in a PCIe x16 slot, but a PCIe x16 card cannot be installed in a PCIe x1 slot.

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