14 Facts About PCI Express


PCI Express, officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards.

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In contrast, PCI Express is based on point-to-point topology, with separate serial links connecting every device to the root complex .

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Furthermore, the older PCI Express clocking scheme limits the bus clock to the slowest peripheral on the bus .

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The PCI Express standard defines link widths of x1, x2, x4, x8 and x16.

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The PCI Express bus has the potential to perform better than the PCI-X bus in cases where multiple devices are transferring data simultaneously, or if communication with the PCI Express peripheral is bidirectional.

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PCI Express is one example of the general trend toward replacing parallel buses with serial interconnects; other examples include Serial ATA, USB, Serial Attached SCSI, FireWire, and RapidIO.

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PCI Express Mini Card, based on PCI Express, is a replacement for the Mini PCI form factor.

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An example of the uses of Cabled PCI Express is a metal enclosure, containing a number of PCIe slots and PCIe-to-ePCIe adapter circuitry.

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OCuLink is an extension for the "cable version of PCI Express", acting as a competitor to version 3 of the Thunderbolt interface.

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PCI Express is a layered protocol, consisting of a transaction layer, a data link layer, and a physical layer.

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PCI Express requires all receivers to issue a minimum number of credits, to guarantee a link allows sending PCIConfig TLPs and message TLPs.

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PCI Express operates in consumer, server, and industrial applications, as a motherboard-level interconnect, a passive backplane interconnect and as an expansion card interface for add-in boards.

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For example, making the system hot-pluggable, as with Infiniband but not PCI Express, requires that software track network topology changes.

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PCI Express falls somewhere in the middle, targeted by design as a system interconnect rather than a device interconnect or routed network protocol.

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