PCI Express


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PCI Express

A high-speed hardware interface from Intel for connecting peripheral devices. Introduced in 2002 as "Third Generation I/O" (3GIO), PCI Express (PCIe) superseded both PCI and PCI-X, and new motherboards may come with a mix of PCI and PCIe slots or only PCIe. See PCI-X.

Since the mid-2000s, computer motherboards have at least one PCIe slot for the graphics card. PCIe is also used for internal Wi-Fi cards, 10 Gigabit Ethernet cards, hard drives and solid state drives (SSDs). See SATA Express.

Switched Architecture - Multiple Lanes
Rather than the shared bus structure of PCI, PCIe provides a switched architecture of channels that can be combined in x2, x4, x8, x16 and x32 configurations, creating a parallel interface of independently controlled "lanes." The switch backplane determines the total bandwidth, and cards and motherboards are compatible between versions.

Internal and External for Laptops
A mini version of PCIe was developed for laptops (see Mini PCI Express) and ExpressCard and Thunderbolt interfaces are sometimes used to extend PCI Express outside the computer (see external GPU). For PCI/PCI Express comparisons, see PCI-SIG. See PCI, ExpressCard, Thunderbolt, PCI-X and SATA Express.

                Data TransferPCI Express      (Bytes/Sec)Version      1 Lane      16 Lanes

    1.0        250 MBps     4 GBps
    2.0        500 MBps     8 GBps
    3.0          1 GBps**  16 GBps**
    4.0          2 GBps**  32 GBps**
  ** = rounded


Different Size Slots
PCIe is not plug compatible with PCI. The x1 slot is a single-lane implementation, while the x16 slot supports 16 lanes for high-speed data transfer.







Parallel Transfer in Serial Form
Each lane is an independent single-bit serial channel on the PCIe backplane.







Only PCIe on the Motherboard
This Asus Z87 motherboard has four x1 and three x16 PCIe slots and no PCI. The x16 slots accept x16, x8 or x4 cards. (Image courtesy of ASUStek Computer Inc.)







AGP to PCI-Express
The AGP slot gave way to an x16 PCI Express slot for the graphics card. The cards have different edge connectors to ensure they plug into the right slot. (Image courtesy of NVIDIA Corporation.)
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