What’s the Difference Between PCI, AGP and PCI-Express?

Do you know the difference between PCI, AGP and PCI-Express? There are many folks out there who sometimes get confused by these terms.

This article is an attempt to clear up this confusion. PCI and PCI-Express are by themselves not a video interconnects, but AGP is a pure video interconnect.

Understanding the difference between PCI, AGP and PCI-Express will go a long way in your understanding of computer technology in general. So read on ...



1. PCI

PCI stands for 'Peripheral Component Interconnect'. This is a connection within the system motherboard that has been used for the last ten years in the world of computing (I think). There is a plethora of products available for PCI. These include sound cards, video cards, LAN cards and RAID controllers. The predecessor to PCI was ISA - which was one of the earlier connection types in the modern PC.




2. AGP

AGP stands for 'Accelerated Graphics Port'. It used to be that video cards were installed on the PCI bus. The problem was data transfer rate. The speed at which the PCI bus transfers data to and from the video card was too slow.

Hence, the AGP bus was launched to increase the data transfer rate of video cards. There are three specification of AGP - they are AGP 1.0, 2.0 and 3.0. The latest incantation of AGP is AGP 3.0. AGP data transfer is faster than PCI, but it is slower than PCI-Express.

The fact that AGP is a pure video interconnect (but not PCI and PCI-EXpress) is a key difference between PCI, AGP and PCI-Express.





3. PCI-Express

PCI-Express is the latest incantation of peripheral interconnections. It is destined to replace both PCI and AGP, especially in the world of video cards. More products are slated to be released that support PCI-Express. Most modern motherboards have PCI-Express built-in. The speed of PCI-Express is another key difference between PCI, AGP and PCI-Express.

PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe (or PCI-E, as it is commonly called), is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP standards. PCIe 2.1 is the latest standard for expansion cards that is available on mainstream personal computers.

LOL, great stuff... thanx for the tut ! Keep them coming!