90 nanometer low-k process
278 million transistors on each of two 7900 chips
HDR
MultiSample Anti-Aliasing
Transparency Anti-Aliasing
DirectX 9.0C
Pixel Shader 3.0
Vertex Shader 3.0
2x16 ROPs
2x8 Vertex Shader Pipelines
2x16 Pixel pipelines
500MHz core clock
600MHz/1.2GHz memory clock

Each 7900 chip on the 7950GX2 is manufactured on TSMC’s 90 nanometer low-k process. The total power needed by the card is less than 143 Watts. The PCI Express x16 slot provides 75W power maximum, an external power connector provides the additional power needed from the power supply. The 7900 chip is almost ½ the size in terms of die size compared to the main competition, the ATI X1900XTX cards. Each chip on the 7950GX2 has 278 million transistors, bringing the total to 556 million transistors.

Earlier I talked about inflection points for video cards. The last inflection point was the introduction of Shader Model 3.0 cards in the form of the 6800 series in 2004. Every card released by NVIDIA after the 6800 Ultra also supports SM 3.0. Pixel Shaders are small programs performed on pixels. Games that use Pixel Shaders include Oblivion, F.E.A.R, Ghost Recon Advanced Warfighter and more. Oblivion has shiny reflective and refractive water made possible by Pixel Shaders. Other effects in the game include materials like wood, bricks, and other objects.

The 7950 GX2 from EVGA is clocked at the default rate of 500MHz for the core and 600MHz for the memory. Each chip has 24 Pixel Shaders, meaning the combination gives a total of 48 Pixel Shader pipelines. Likewise there are 16 Vertex Shaders and a total of 32 outputted pixels a second from the 7950 GX2. With two 7950 chips, the 7950 GX2 has 1GB of DDR3 memory total. Each chip has 512MB of memory assigned to it, with a 256-bit memory bus. Total memory bandwidth is 600MHzx32 (256-bit/8)x2 or 38.4GB/second on each card of the two (76.8GB/second total).

One of the big features of games today is High Dynamic Range Rendering or lighting. The human eye can distinguish between thousands of contrasting colors at a time. With integer based lighting, early video cards could only show a contrast ratio of 255:1. Video cards with floating point calculations like the GeForce 7950 GX2 can use floating point blending operations to give natural lighting in games. Oblivion uses HDR in virtually every scene, with the sky in the game having a glow effect.

A big benefit of SLI is the increased Anti-Aliasing modes available to the video cards. The 7900 is capable of doing AA in 2x, 4x, 6XS, 8XS modes. 6XS mode is 2X MSAA+2x SSAA combined. 8XS mode is 4X MSAA+2X SSAA combined. With two 7900 chips on the card working together in SLI there are two new modes, 12X and 16X. 12X mode works by having each chip do 6XS in an offset position. 16X works by having each chip do 8XS in an offset position. The 7xxx series also introduced Transparency Anti-Aliasing into NVIDIA cards. TAA applies SuperSample or MultiSample AA to transparent textures such as the inside of a chain-link fence or dense vegetation.