AGP 8x announced

Ever wondered what AGP actually is and why there are different versions of it?

Yesterday CPU giant and motherboard chipset manufacturer Intel proudly unveiled its draft spec for AGP 8x (you will need Acrobat installed to read that file), which has caused quite a noticeable stir amongst those in the know, using all sorts of new techniques to increase the bandwidth of the port. However, we would be naive to suspect that amidst all the oo'ing and aar'ing there weren't a number of people scratching their chins and wondering, just what the heck is AGP anyway? And from a gamer's point of view, why should I be interested? You no doubt realise that AGP stands for Advanced Graphics Port, and comes in several flavours, AGP 1x (or just AGP), AGP 2x, AGP 4x and AGP Pro. The concept is thus; back in the day, all graphics cards were either ISA or PCI, PCI being the more up to date and common. A PCI graphics card though, was restrained in its performance by several factors. Not only the data transfer rate between the PCI Bus and the CPU (which was an incredibly limiting factor by today's standards), but also the problem that a lot of cards were trying to share that narrow pathway of data. So when the AGP port was created, it was heralded as a chariot of gold so to speak for all the lovely data your graphics card wanted to push back and forth between it, the processor and other areas of your computer. By using this new, isolated transfer mechanism running at 66MHz independant of the PCI bus, the amount of bandwidth allocated to the graphics card became ludicrously big, and AGP was clearly here to stay. With the introduction of AGP 2x, the bandwidth doubled, and 2x is where a lot of people using the BX chipset (Intel's most widespread desktop motherboard chip) still are today. Newer motherboards have now supported AGP 4x for quite some time, but there were cries about its stability at first, and as it doesn't actually improve performance over AGP 2x by that much in a handful of the top-selling graphics cards, not too many people are all that bothered by it. AGP Pro is, well, an experimental technology you could say, which hasn't really been put to good use just yet. So AGP 8x (which may not be with us until 2003 at this rate) once again improves the situation for this ham-fisted graphics card producers. Of some interest is that the new bus will also support Intel's 64-bit processor Itanium and its successors, but more importantly, thanks to a technique similar to that of the Athlon's DDR front side bus, the 66MHz bus frequency is to be effectively doubled by using of the rising and falling edge of the clock signal. Confused? Well, currently, a clock signal is sent at 66MHz, and the card occupying the AGP slot can use one side of the clock signal (which rises and falls) to transfer data. The Athlon introduced a new technique which allowed motherboard manufacturers to utilize the rising and falling edge of the clock signal as well, doubling the transfer throughput as a result. Intel will now take advantage of a similar technique to allow its AGP 8x spec to double throughput. All this along with a proposed bandwidth of 2Gb/second means AGP 8x will be a force to be reckoned with when the time comes. For gamers, this means more high resolution graphics at faster speeds and with less jerking. With a high enough speed processor and an AGP 8x graphics card, you could expect performance far in excess of anything we can imagine today.

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About the author

Tom Bramwell

Tom Bramwell

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Tom worked at Eurogamer from early 2000 to late 2014, including seven years as Editor-in-Chief.

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