Peripheral Component Interconnect Express - What is PCIe?

Peripheral Component Interconnect Express, or PCIe, is a physical interconnect for motherboard expansion. Normally this is the connector slot you plug your graphics card, network card, sound card, or for storage purposes, a RAID card into. PCIe was designed to replace the older PCI, PCI-X, and AGP bus standards and to allow for more flexibility for expansion. Improvements include higher maximum bandwidth, lower I/O pin count and smaller physical footprint, better performance-scaling, more detailed error detection and reporting, and hot-plugging. The physical connector on the motherboard typically allows for up to 16 lanes for data transfer. A PCIe device that is an x4 device can fit into a PCIe x4 slot up to an x16 slot and still function. PCIe 1.0 allowed for 250MB/s per lane, PCIe 2.0 allows for 500MB/s per lane and the newest PCIe 3.0 allows for 1GB/s per lane.

PCI-Express Speeds