AGP 8X A Closer Look
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AGP 8X technology has recently been introduced by NVIDIA, ATI and SiS for improved performance on their current video card solutions. These companies are consistently striving to increase video performance in the state of the PC industry. More bandwidth, higher throughput, higher utilization, faster core and memory speeds, smaller die size. Anything possible to gain an edge over the competition.
AGP 8X A Closer Look
Introduction
AGP 8X technology has recently been introduced by NVIDIA, ATI and SiS for improved performance on their current video card solutions. These companies are consistently striving to increase video performance in the state of the PC industry. More bandwidth, higher throughput, higher utilization, faster core and memory speeds, smaller die size. Anything possible to gain an edge over the competition.
SiS was the first company on the scene to introduce an 8x AGP capable video card (the Xabre 400) and all other companies have consequently followed suit. We are still waiting for the chipset industry to fully adopt the new standard but it surely won't be long. SiS was again first on board and will soon be joined by Intel, VIA and AMD who have plans to fully support AGP 8X in their chipsets as well.
Today I'd like to give some thoughts and observations into what benefit (if any) that you can look for when moving from the current AGP 4X standard to the newer and faster AGP 8X. In addition to highlighting a few of the key technologies used with AGP 3.0.
History
The Advanced Graphics Port (AGP) was first introduced back in 1996 as simply AGP1.0. AGP 1.0 incorporated both the AGP 1X and 2X specifications and it was up to the individual chipset manufacturers on which spec to run with. As with any new technology, there was a trial period to get all the bugs worked out and eventually, AGP simply became "the standard". Everyone came on board to support both AGP 1X and 2X which greatly increased bandwidth over the aging PCI video form factor. Initially the gains were small, but once the hardware matured, and software was devised to take advantage of the added bandwidth, we then were able to fully benefit from the new and emerging technology, which eventually led to the improved 4X spec (AGP2.0) and finally where we are today at the 8X AGP spec, also known as AGP3.0. AGP3.0 spec doubles the bandwidth of AGP 2.0 to 2.1GB/sec. After moving from from AGP 2X to 4X, the reality of double the performance never quite materialized, and I suspect we will see the same with 8x. But more on that later.

Below is a quick reference to keep in mind throughout this article.
AGP 1.0 - AGP 1X - 2X
AGP 2.0 - AGP 4X
AGP 3.0 - AGP 8X
What is AGP?
"AGP is a high-performance interconnect between the core-logic chipset and the graphics controller for enhanced graphics performance for 3D applications. AGP relieves the graphics bottleneck by adding a dedicated high-speed interface directly between the chipset and the graphics controller as shown below."

Thanks to Intel Corp. we have a basic understanding of what AGP is and does. Graphic intensive applications were simply too much to handle for the PCI bus and had to be moved to it's own section in order to keep up with the data hungry needs of today's video performance requirements. Thus AGP was born.
What is AGP3.0?
AGP3.0 introduces the natural progression from AGP2.0. AGP 8X technology delivers over 2.1GB/sec. of bandwidth and will be the standard for at least the next few year and/or new specifications are announced.
Specifications
On paper, AGP 8X gives the impression of double the performance over 4X. Omitting several other factors, this may very well be true. But what may appear in real world and synthetic benchmarks could reveal quite a different story. Lets break it down by the numbers.

Looking at the chart above. We are lead to believe that with each latest revision of the AGP spec will offer up quite a bit of added performance. Keep in mind we are looking at AGP (BUS) bandwidth, and not actual performance numbers. Next I want to show you a chart found on nVidia's very own website.
| Product | GF4 Ti 4600 | GF4 Ti 4400 | GF 4 Ti 4200 w/8X | GF4 Ti 4200 |
| Fill Rate | 4.8 Billion | 4.4 Billion | 4 Billion | 4 Billion |
| Vertices/sec. | 136 Million | 125 Million | 113 Million | 113 Million |
| Memory Bandwidth | 10.4GB/sec. | 8.8GB/sec. | 8GB/sec. | Up to 8GB/sec. |
| Max Memory | 128MB | 128MB | 128MB | 128MB |
Almost odd that they would publish these numbers that do not necessarily shine a bright light on the capabilities of AGP 8X . Nevertheless, the numbers are correct and I would even go so far as to give nVidia a pat on the back for showing it like it is.

Confused yet? Me too. But lets not confuse Memory Bandwidth with AGP, or "Bus" Bandwidth. This is where the improved 8X AGP spec comes into play. Providing massive amounts of data movement between main memory and the graphics subsystem, eliminating bandwidth bottlenecks we have come to expect from AGP 4X and below. This in turn will move large and complex textures faster when needed. And the ultimate goal of this evolutionary step is provide the end user with cinematic or lifelike graphics in real-time. Can you imagine playing a game in real-time that looked like Final Fantasy the movie? We aren't quite there yet. And won't be for a few more years, but it's coming, you can count on that, and steps moving forward in video technology such as 8X AGP will eventually bring that to fruition. We are certainly looking forward to Doom3's release next year as it is gearing up to give us our best gaming experience yet. Those of you who have checked out the leaked demo know what I'm talking about. The gaming visuals are absolutely incredible, and also bring all current video cards to their knees running a higher resolution and quality graphics options enabled. By the time it is released however, the video cards available with AGP 8X coupled with DDRII should perform much better.

Next: AGP 8x A Closer Look >>
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