The PCI Express Architecture defines a flexible, scalable, high-speed, serial, point-to-point, hot pluggable/hot swappable interconnect that is software-compatible with PCI.

The foundation of the PCI Express Architecture was laid in the Arapahoe Working Group under the code name Third Generation I/O or 3GIO (the first two generations being the ISA and PCI/PCI-X buses). In early 2002, it was re-named the PCI Express Architecture.

Key features of the PCI Express Architecture Base Specification are:

  • Compatibility with current PCI enumeration and software device driver models.
  • Each point-to-point interconnect may have 1, 2, 4, 8, 12, 16, or 32 dual simplex 2.5 Gbps lanes (2.0 Gbps effective rate), providing scalable bandwidth to 128 Gbps (16 gigabytes/second) between nodes.
  • Predictable latency to enable applications requiring isochronous data delivery.
  • Native Hot Plug/Hot Swap capability.
  • Native Power Management capability.
The PCI Express Architecture is intended to replace AGP. The first generation of PCI Express Architecture provides twice the bandwidth of AGP8X. Additionally, the PCI Express Architecture supports multiple graphics I/O devices in a single system.