What is the Difference Between PCI and PCI Express

The main difference between PCI and PCI Express is that the PCI is a parallel interface while PCI Express is a serial interface.

PCI is a bus that allows connecting devices inside the computer to extend its capabilities. The original PCI standard provides a data transferring rate of 133 Mbps. The PCI Express is the latest version of PCI. It is an improved version. It provides a higher system bus throughput, better performance scaling for bus devices, and detailed error detection and reporting methods.

Key Areas Covered

1. What is PCI
     – Definition, Functionality
2. What is PCI Express
     – Definition, Functionality
3. What is the Difference Between PCI and PCI Express
     – Comparison of Key Differences

Key Terms

PCI, PCI Express

What is PCI

PCI stands for Peripheral Component Interconnect.  It is a hardware bus that helps to add internal components to a desktop computer. It uses a parallel bus structure. Moreover, it is possible to insert a PCI card to a PCI slot on a motherboard to provide additional IO ports.

PCI architecture is also known as conventional PCI. This technology was introduced in 1992 by Intel. In earlier computers, there were two to five PCI cards. Each card required an open slot on the motherboard. Furthermore, it required a removable panel on the back of the system unit. Adding PCI cards was an easy way to upgrade a computer because it helps the users to add better video cards, faster wired or wireless networking or add new ports like USB 2.0.

Figure 1: PCI and PCI Express Slots

The original 32bit, 33MHz PCI standard was capable of sending and receiving data at a rate of 133Mbps. The 64bit, 66MHz is an upgraded standard that supports a faster data transferring rate at a frequency up to 533 MHz. In the year 1998, the organizations IBM, HP, and Compaq introduced PCI –X (PCI extended). It provides a data transferring rate up to 1064MHz. Furthermore, it is backward compatible with PCI.

What is PCI Express

The latest PCI version is PCI Express (PCI e). It uses a network of serial connections controlled by a hub on the computer’s motherboard. Therefore, PCI Express cards run faster than general PCI cards. There must be at least one PCI Express Slot available on the computer in order to use the PCI Express card.

PCI Express is available in x1, x4, x8, and x16 implementations. They increase the bandwidth by corresponding amounts. The larger implementations require longer PCI Express slots. The x16 is the largest slot while x1 is the smallest slot. It is possible to insert PCI Express card slots to any slot that is large enough for it. For example, x4 can be inserted to x8 but not to x1.

The main advantage of PCI Express is that it provides fast data transfer rates. It is possible to connect high-speed devices such as high-end video card and Gigabit Ethernet cards using PCI Express. Therefore, PCI Express is capable of replacing PCI. Furthermore, PCI Express is backward compatible with PCI hardware and software.

Difference Between PCI and PCI Express

Definition

PCI is a local computer bus for attaching hardware devices in a computer. On the other hand, PCI Express is a high-speed serial computer expansion bus that is designed to replace older PCI and PCI – X bus standards.

Long Form

Moreover, PCI stands for Peripheral Component Interconnect while PCI Express stands for Peripheral Component Interconnect Express.

Interface Type

The main difference between PCI and PCI Express is that the PCI is a parallel interface while the PCI Express is a serial interface.

Speed

Speed is another difference between PCI and PCI Express. PCI Express provides a faster data rate than PCI.

Slot Type

While PCI slots are standardized, PCI Express depends on the number of lanes the slots are intended for.

Version

PCI Express is the latest version while PCI is the older version.

Conclusion

In brief, PCI Express is a newer version of PCI, which provides faster speed. The main difference between PCI and PCI Express is that PCI is a parallel interface while PCI Express is a serial interface.

Reference:

1. “PCI.” P2P (Peer To Peer) Definition, Available here.
2. “PCI Express.” P2P (Peer To Peer) Definition, Available here.
3. “PCI Express.” Wikipedia, Wikimedia Foundation, 5 Dec. 2018, Available here.

Image Courtesy:

1. “PCI und PCIe Slots” By The original uploader was Smial at German Wikipedia. – Transferred from de.wikipedia to Commons (CC BY-SA 2.0 de) via Commons Wikimedia