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 ...
What a typical AGP video card
looks like
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.
