PCI (Peripheral Component Interconnect)

Peripheral Component Interconnect (PCI) is an example of a parallel expansion bus (and a corresponding slot type) used for attaching hardware devices (in the form of an integrated circuit or expansion card) to the motherboard inside the computer case.

Conventional PCI Properties

  • 32-bit bus width
  • 64-bit bus width
  • Parallel interface
  • Maximum throughput of up to 533 MB/s

PCI-X Properties

Peripheral Component Interconnect eXtended (PCI-X) is an advanced version of PCI which:

  • Doubles the bandwidth of PCI, Provides much faster data transfer rates in comparison to PCI
  • Offers backward compatibility with PCI devices
  • Didn’t get much of a market success due to the development and widespread adoption of the PCIe standard
  • Was intended for devices with higher bandwidth requirements such as servers and high-end workstations

PCI-X Hardware Standards

The PCI-X standard was defined by these characteristics:

  • Parallel interface
  • Maximum throughput of up to 1064 MB/s
  • 64-bit bus width

What is PCIe?

PCI Express (Peripheral Component Interconnect Express), abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard that relies on serial communication.

What did PCIe Replace?

Peripheral Component Interconnect Express (PCIe) is a high-speed, serial expansion bus designed as a replacement for:

  • PCI
  • PCI-X
  • AGP

What is a PCIe Lane?

In PCIe architecture, a single full-duplex point-to-point serial communication path consisting of two pairs of wires (where one pair is used for transmitting data and the other pair for receiving data) is known as a Lane.

PCIe Labeling Lanes and Throughput

The PCIe labeling (×1, ×4, ×8, ×12, ×16 and ×32) refers to the number of communication links (lanes) available in different versions of the PCIe interface. The base value (x1) relates to the speed of a single lane expressed in MB/s. The multiplier (x) allows for easy calculation of the maximum throughput of the entire interface for a given PCIe variant.

PCI Express
Introduced Line
×1 ×2 ×4 ×8 ×16
1.0 2003 8b/10b 2.5 GT/s 250 MB/s 0.50 GB/s 1.0 GB/s 2.0 GB/s 4.0 GB/s
2.0 2007 8b/10b 5.0 GT/s 500 MB/s 1.0 GB/s 2.0 GB/s 4.0 GB/s 8.0 GB/s
3.0 2010 128b/130b 8.0 GT/s 984.6 MB/s 1.97 GB/s 3.94 GB/s 7.88 GB/s 15.8 GB/s
4.0 2017 128b/130b 16.0 GT/s 1969 MB/s 3.94 GB/s 7.88 GB/s 15.75 GB/s 31.5 GB/s
5.0 expected in
Q1 2019
128b/130b 32.0 GT/s 3938 MB/s 7.88 GB/s 15.75 GB/s 31.51 GB/s 63.0 GB/s


What is Mini PCI?

Mini PCI is a type of PCI slot for expansion cards installed in laptops characterized by a much smaller form factor when compared to its desktop counterpart.

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