XFX 7800GS AGP Extreme Edition Review :: The Features

• 0.11 micron process
• 302 million transistors
• DirectX 9.0c
• Pixel Shader 3.0
• Vertex Shader 3.0
• HDR
• MSAA
• Transparency SuperSample and Multisample Anti-Aliasing
• Up to 16X Anisotropic Filtering
• 8 ROPs
• 16 Pixel Shader pipelines
• 6 Vertex Shader Pipelines
• 375MHz Core Clock (Standard Edition)
• 440MHz Core Clock (Extreme Edition)
• 1.2GHz Memory Clock (Standard Edition) GDDR-3
• 1.3GHz Memory Clock (Extreme Edition) GDDR-3
• 256MB Memory
• 256-bit memory bus
• AGP bus

XFX decided to release two versions of the 7800GS AGP card, the Standard Edition and the Extreme Edition. The Standard Edition has the same reference core clock speeds as the NVIDIA reference card, 375MHz.The Extreme Edition has the core clock increased to 440MHz, a 65MHz increase over the reference design. The card I received from XFX was the Extreme Edition.

NVIDIA first introduced their first Shader Model 3.0 parts in 2004 with the launch of the NV4x series. The cards available based upon that series included the 6800 Ultra, the 6800GT, the 6800, the 6800GS on the high-end/performance range to the 6600GT and 6600 for the mid-range and the 6200 for the casual gamer or value segment. Later iterations included the 6800XT, the 6600 256MB, and the 6200 with Turbo Cache. The 6800 Ultra was the last NVIDIA card to feature

The 7800GS is an interesting card in terms of pipelines. The 7800GS has 16 Pixel Shader Pipelines. This is the same number as found on the 6800 series of cards, but less than the 24 PS pipelines on the 7800GTX and the 20 PS pipelines on the 7800GT. Further, NVIDIA decided to limit the outputted pixels to 8 per clock instead of the 16 on the 7800GTX and 7800GT. The 7800GS AGP is based upon the 0.11 micron process, with over 300 million transistors, just like its bigger brothers.

Last June NVIDIA introduced their second Shader Model 3.0 generation, the G7x series with the introduction of the GeForce 7800GTX cards. Later last year they introduced the 7800GT, the $399 part. At the beginning of 2006 NVIDIA introduced their value part based upon this architecture, the 7300GS. But there's a missing piece to their lineup, unfilled since the 6800 Ultra of 2004, the AGP cards.

Pixel Shader 3.0 is the minimum requirement for any video card I recommend today, luckily both NVIDIA and ATI have PS 3.0 parts throughout their lineups, with only one or two exceptions. The key features of PS 3.0 include: dynamic branching and looping, nearly infinite Pixel Shader program lengths, double faced register for two-sided lighting and more. Pixel Shaders are used in virtually every game released today. Games like F.E.A.R., Age of Empires III, Half Life 2 Lost Coast make extensive use of Pixel Shaders.

Vertex Shader 3.0 is the third iteration of Vertex Shaders for Microsoft's DirectX API. Key features of VS 3.0 include Render To Texture, Geometry Instancing, nearly unlimited Shader length programs, and more. The GeForce 7800GS has 6 Vertex Shader units, giving a maximum throughput of 660 million vertices a second on the Extreme Edition. The 7800GS is an interesting blend of the 7800 but modified for a different market.

One of the key advances of the 7800 series was the introduction of Transparency Anti-Aliasing. TAA comes in two flavors, Multisample and Supersample on the 7800 series. What TAA does is lessen the aliasing in textures that are transparent. These are not normally affected by the normal rotated grid multisample anti-aliasing used by the NVIDIA GeForce series. TAA is best used where there are gaps like in a chain-link fence or dense vegetation.

High Dynamic Range Rendering is something that requires floating point color precision. The human eye can distinguish between thousands of contrasts. The old video cards with Integer hardware could show a maximum of 255:1 contrast ratio. The GeForce 7800GS AGP is capable of FP32 calculations, allowing for a maximum contrast ratio of 65,536:1. HDR is used quite effectively in games like Serious Sam 2, HL2 LC and more.