Difference between a PCI and and AGP Video Card


OSNN Senior Addict
Hi. What is the main difference between a PCI board type video card and an AGP video card? Which is faster and more reliable? Thanks.


The One and Only
uuh.... i take it you mean AGP and PCI-Express. BIG difference between PCI-Express and PCI. as for the difference between agp and pci-express..... as of right now i'm not sure if there's a very noticable performance difference between the two, since i'm not sure if the PCI-Express bus has been fully used yet.... but supposedly it has a much higher processing speed between the card itself, memory, and the CPU. god do i wish i'd read up more on what all the differences were between all this stuff. i think PCI-Express is also on it's own bus, where i believe AGP shared the PCI bus (someone PLEASE correct me on this if i'm wrong..... or say if i've pretty much got it...)

Basically.... if what you're saying is more or less somewhat of a question leading up to an upgrade decision.... i'm sure everyone would agree that with the specs of your system, PCI-Express would be a better route to go over AGP, mostly because then it's kind of future-proof, unless they come out with another architecture for video cards (PLEASE GOD NO!!)


Debiant by way of Ubuntu
ElementalDragon said:
uuh.... i take it you mean AGP and PCI-Express. BIG difference between PCI-Express and PCI. ...
ain't necessarily so...

diff remains the same tho'

AGP is dedicated bandwidth (big) for gfx and PCI is shared by all cards in slots and does not have such a fat pipe. PCIX has a fatter poipe but remains shared, also because it is new it commands a premium.

There is a third way - but I have forgotten what it is... I feel sure someone with better memory will expand on that in this thread though (c'mon guys ;) )
agp was always addressed as pci0 as far as the hardware was concernd - ot was just a pci bus dedicated to the vga card at twice the clock rate as pci. thh 2x 4x and 8x indicated how often per clock pulse data was transmited.

pci-express is like a motorway with little restriction on how many lanes you can build in either direction :)


Blame me for the RAZR's
it all came from here. this will answer your question.
Q:Is PCI Express Video Faster than AGP Video?
A:Yes and No. A 16x PCI Express connection is at least 190% Faster than AGP 8x but this is the connection between the system and the video card. You use the connection the most when your video card is low on memory or when the game you are using uses a Direct X or Open GL feature that isn't supported in hardware.

So, what this means is that in terms of real world performance there may not be a huge difference between AGP and PCI Express if you are talking about identical chipsets. Unfortunately this is very hard to prove because graphics chipsets are designed either for PCI Express or AGP. If you have a card that is available in both forms then you have a graphics chipset that was designed for PCI Express and has a special bridge chip installed to let it comunicate with the AGP bus. The short of this is: if two cards of the same chipset are available in AGP and PCI-E then the PCI-E one will always be faster. On PCI-E you don't have the overhead of the bridge chip so it's faster, and you have the better bandwidth so in intense situations such as high resolution gaming you'll come out on top every time.

The main point here is: If you have a system with AGP on it, it doesn't make sense to upgrade just to get PCI-E video right now. The fastest AGP card to ever come out is likely to be the nVidia 6800GT. If you are at a point where that is too slow then by all means it makes sense to make a complete switch. If your happy with your AGP graphics options, wait until you are ready to upgrade the processor or other components before making the PCI-E switch. For more information on AGP and PCI please see the general FSB guide.
Common Buses and their Max Bandwidth
PCI 132 MB/s
AGP 8X 2,100 MB/s
PCI Express 1x 250 [500]* MB/s
PCI Express 2x 500 [1000]* MB/s
PCI Express 4x 1000 [2000]* MB/s
PCI Express 8x 2000 [4000]* MB/s
PCI Express 16x 4000 [8000]* MB/s
PCI Express 32x 8000 [16000]* MB/s
IDE (ATA100) 100 MB/s
IDE (ATA133) 133 MB/s
SATA 150 MB/s
Gigabit Ethernet 125 MB/s
IEEE1394B [firewire] 100 MB/s

PCI Express is an exciting advance in the area of computers. Although AGP is now starting to die rapidly, standard PCI is taking/will take longer to die off. Expect to see at least 1 or 2 standard PCI slots along side PCI-E in all motherboards for at least the next 2 years. By that time there will be PCI-E replacements for all common devices such as modems, network cards, raid cards, i/o and more.
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