PCI Express - Computer Definition
A high-speed hardware interface from Intel for connecting peripheral devices. Introduced in 2002 and originally known as "Third Generation I/O" (3GIO), PCI Express (PCIe) superseded both PCI and PCI-X, and new motherboards may come with a mix of PCI and PCIe slots or only PCIe. Since the mid-2000s, computer motherboards have had one PCIe slot for a display adapter (graphics card). PCIe is also used for internal Wi-Fi cards, 10 Gigabit Ethernet cards, hard drives and solid state drives (SSDs). Rather than "PCX," the official abbreviation of PCI Express is "PCIe." PCX is too much like PCI-X, another PCI standard (see PCI-X). Switched Architecture - Multiple Lanes Rather than the shared bus structure of PCI, PCIe provides a switched architecture using serial communications channels that provide a 250 MB/sec (PCIe 1.0) and 500 MB/sec (PCIe 2.0) transfer rate per lane. Cards and motherboards are forward and backward compatible between versions. Channels can be combined in x2, x4, x8, x16 and x32 configurations, creating a parallel interface of independently controlled "lanes." The switch backplane bandwidth determines the total capacity. Internal in 2002, External in 2007 External PCIe extends the bus outside the box; for example, from a laptop to a high-end external display adapter (graphics card) in its own housing. A mini version for internal laptop use was also developed (see Mini PCI Express). For data rate comparisons of all PCI technologies, see PCI-SIG. See PCI, ExpressCard, PCI-X and Thunderbolt.