ATI AIW Radeon X800XT AGP Video Card Review :: The Features

• .13um low-k
• 160 million transistors
• Pixel Shader 2.0b
• Vertex Shader 2.0
• 3Dc
• Smooth Vision
• Hyper III+

Based upon ATI's R420 chip the X800XT A-I-W has a 16-pixel pipeline design that formed the basis for virtually every ATI high-end part today. Built on Tam's .13um low-k process, the X800XT has around 160 million transistors. By way of comparison, Intel's 3.6 GHz 660 CPU has around 169 million transistors, most of which comprise the L2 cache on the CPU. NVIDIA's 6800 has 222 million transistors, supporting DirectX 9.0 Shader Model 3.0, but transistor counts don't really mean that much by themselves. The X800XT has 6 vertex shaders giving it a maximum triangle throughput of 750 million theoretical triangles per second.

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The A-I-W X800XT supports the same feature set as the other X800 class cards. DirectX 9.0 and OpenGL 2.0 are fully supported by the chipset. The X800XT supports Pixel Shader 2.0b, and Vertex Shader 2.0. It's capable of executing 1536 Pixel shader instructions in a pass. Of course, this isn't important as you can multi-pass, and most games today are written with Pixel Shader 2.0 in mind (Half Life's longest Pixel Shader is 50 instructions long.) Vertex Shader 2.0 supports up to 65,028 instructions in a single pass through looping and branching.

3Dc is ATI's trademark for Normal Map Compression. A normal map is a texture map that uses RGB channels to determine how lighting on a object is done. By changing the vector of an object you can give the appearance of more detail. Developers use normal maps to give the appearance of more detailed characters. Far Cry, for instance uses NM to make a 1500 polygon character look the same as a 15000-polygon object.

SmoothVision is ATI's trademark for image enhancing algorithms like Full Scene Anti Aliasing and anisotropic filtering. ATI's X800 card can use up to six samples Multi Sample Anti Aliasing (MSAA) in a pattern that is sort of a rotated grid. In games that can maintain more than 60FPS, the user can use Temporal Anti Aliasing. TAA uses differing sample positions for different frames then combining the image to give the illusion of higher level of anti-aliasing than actually used.

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