From LQWiki

PCI or Peripheral Component Interconnect is a local bus standard that was developed by Intel. It is 64 bits wide (though mostly implemented in 32 bits) and can run at frequencies of 33Mhz or 66Mhz. The throughput available at 33Mhz and 32 bits is 133Mbits per second.

It is widely used for network interface cards, sound cards, IDE interfaces, and just about everything else under the sun. However, due to its bandwidth limitations a new standard based on PCI has emerged, called PCI-X or PCI Express.

PCI-X is a 64bit bus that runs at 133Mhz and has an available bandwidth of more than 1000Mbits per second (or 1Gbit per second) and was developed by HP, IBM, and Compaq. PCI-X is also set to displace the venerable AGP bus.

PCI replaced the older ISA bus.

See also

• lspci - command to list devices to pci interface