PCI Express

PCI Express (PCIe Base Spec 1.1) is a specification which defines an open standard for supporting PCI Express protocols on multiple form factors. This specification is released under PCI SIG's procedures.

PCI Express, or PCIe, (formerly known as 3GIO for 3rd Generation I/O, not to be mistaken for PCI-X) is an implementation of the PCI computer bus that uses existing PCI programming concepts, but bases it on a completely different and much faster serial physical-layer communications protocol. The physical-layer consists not of a bus, but of a network of serial point-to-point links much like twisted pair ethernet.

PCI Express is intended to be used as a local interconnect. As it is based on existing PCI system, cards and systems can be converted to PCI Express by changing the physical layer only – existing systems could be adapted to PCI Express without any change in software. The higher speeds on PCI Express allow it to replace almost all existing internal buses, including AGP and PCI, and Intel envisions a single PCI Express controller talking to all external devices, as opposed to the northbridge/southbridge solution in current machines. Review an overview of the PCIe architecture.
 
The PCI Express protocol can be implemented in many different form factors. Some of those form factors include: