The 7800GT is based upon NVIDIA’s G70 chip. This chip is based upon the same family as the 7800GTX but with 4 less pixel pipelines (20 instead of 24) and one less vertex Shader pipeline (5 instead of 6). NVIDIA chose to use the .11 micron process from TSMC instead of the newer .09 micron process ATI will use in their upcoming products (R520). The chip has over 302 million transistors, an increase of over 80 million over the previous generation 6800 series.

Key features of the 7800GT include support for Microsoft’s DirectX 9.0c Pixel and Vertex Shader 3.0. Pixel Shaders are small programs performed on pixels to do special effects including realistic skin and blood vessels, realistic water and armor, and other effects. Microsoft introduced DirectX 9.0 in late 2002, with 2 different versions of Pixel Shaders 2.0 and 3.0. ATI will introduce new cards in the next month with support for this feature, but at the moment no x1800/1600/1300 cards are out at retail. Vertex Shaders are small programs performed on vertices. Effects that can be done with VS include deformation of water, matrix skinning, realistic cloth animation and more.

Transparency Antialiasing is a feature introduced with the 7800GTX. Antialiasing cures visual artifacts caused by having lines that are thinner than a pixel. Aliasing often gives the look of a “jagged line” or “stair step” type pattern. Thin-lined objects such as chain-link fences and vegetation aren’t Antialiased with normal Multisample Antialiasing, but with NVIDIA’s Transparency AA the interior looks a lot better. NVIDIA offers two different versions of Transparency AA with the 7800 series, MultiSample and SuperSample AA. SSAA looks better in more situations than MSAA, but the performance with MSTAA is higher. PureVideo is NVIDIA acronym for their video processing software. The features of PureVideo include Video Shaders, features for Home Theaters, and a HD (High Definition) decoder. NVIDIA’s PureVideo is available on their website for the price of $29.99. If you have a good decoder like WinDVD or other decoder, the PureVideo decoder may not be of much use, as I found the playback with PureVideo to be on-par or below WinDVD.