AGP Video Card

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AGP video cards are still among the fastest and most powerful video cards produced today, although with the advent of PCI-Express their days as the preferred bus for graphics processing is over… for now.

AGP Video Card


Advantages of AGP

The AGP bus was invented to circumvent a problem with the current PCI bus architecture. The issue was that that the PCI bus was slow, and that cards farther away from the CPU took longer to send and receive their data, since the cards in front of them on the bus had a higher priority. This meant that video cards on the PCI bus had to effectively “wait in line” as other PCI devices communicated with the CPU. Thus the AGP bus was invented so that video cards could have a direct link to the CPU.

The AGP bus also introduced several more improvements over the old PCI bus, namely priority queues and pipelining. Priority queues allow each instruction to carry a priority with it, so that critical instructions are processed before non-essential instructions. The other improvement, pipelining, is a system where the graphics processor is able to work on multiple steps of an instruction concurrently. The more pipelines the graphics processor supports, the quicker the GPU can process the instruction. These two features helped make AGP even more attractive to video card developers, and has made the current generation of video cards possible. Even with all those improvements, the AGP was little more than a dedicated graphics PCI bus with some added features.


The Future of AGP

Upon release, the bus was widely successful, and in 1997 was further improved with the release of AGP 2x, which doubled the memory bandwidth from 266 MB/s to 533MB/s. Subsequent doubling of the technology produced AGP 4x and today’s current AGP 8x bus architecture which has 2.1GB/s memory bandwidth. It looks at this point that further AGP development is doubtful, however. With the release of the PCI-Express bus architecture, running at 16x (4.1GB/s) and utilizing dual channel communication through the PCI-Express bus, AGP is effectively dead for the time being.

Most new systems today are being produced with PCI-Express slots instead of AGP. However if you bought a computer even just 6 months ago, you might be stuck with your AGP video card. Instead of buying a new motherboard or computer just to upgrade to PCI-Express, I recommend looking at all the available AGP video cards that are still being produced. Irregardless of the future of AGP, there are still several high end AGP video cards out there that can give your system the power it needs to rip through today’s next generation games. For example, the NVIDIA GeForce 6800 GT is available as an 8x AGP graphics card as well as PCI-Express, with little to no difference in actual performance between the two. The reason for the similar performance is that the memory bandwidth available on the PCI-Express is not yet really being taken advantage of. However, in the future, as cards continue to need more and more memory bandwidth, the PCI-Express cards will start to show their true potential.