NVIDIA’s NV4x architecture was the first Shader Model 3.0 architecture on the market when announced in April of last year. What this means is, the cards based upon it supported Pixel Shader 3.0 and Vertex Shader 3.0. I’ll briefly cover the major features here. The 6800 Ultra and GT are 16 pipeline cards and among the fastest, most feature-rich video cards on the market today. The 6600GT has half the pixel pipelines in most instances but the same number of vertex shaders as its bigger brothers.

Pixel shaders are small programs performed on pixels allowing for effects like realistic looking skin (witness NVIDIA’s Dawn or Dusk demos), realistic looking water (almost any game with pixel shaders today, and realistic armor. PS 3.0 adds branching and looping to the pixel shader feature list, allowing for nearly infinite length pixel shaders. NV4x also is the first NVIDIA family to support Multiple Render Targets also known as deferred shading.

Vertex Shaders are programs performed on vertices. Effects that can be done with vertex shaders include geometry instancing, displacement mapping, render to texture. Geometry instancing allows one model to be animated many different ways, saving rendering time. Displacement mapping can add geometry to a model, affecting the way light interacts with the model and can show far more detail than simply bump mapping the model allows.

PureVideo is NVIDIA’s trademark for their video improvement technology. The PureVideo processor (the 6600GT in this case) offloads high definition video encoding from the CPU to the video card, providing nearly stutter-free performance when playing back high-definition content like HD-DVD or HDTV. The key features of PureVideo include: a motion estimation engine, High-Definition MPEG-2 Hardware Acceleration, Windows Media Video High-Definition Hardware Acceleration, Advanced Spatial-Temporal De-Interlacing, 3:2 Pull-down Correction, 3:2 Edit Detection and Correction, and Multi-Stream VMR Scaling.

3dfx introduced the concept of SLI (Scan Line Interleave) back in 1997 with the launch of the Voodoo 2. 3dfx, along with NVIDIA and ATI redefined the world of video cards to need 3d graphics. Last year, NVIDIA announced the nForce4 SLI chipset supporting dual PCI Express video cards on the same motherboard. NVIDIA’s SLI stands for S Earlier this year, NVIDIA announced the nForce4 for Intel SLI chipset. SLI on NVIDIA cards can increase performance in games and applications up to 85-90%, some get more benefit from SLI than others. AOpen did not provide two 6600GTs, so unfortunately I will just make a mention of SLI in this review.

Clock speed on the AOpen 6600GT is 500 MHz for the core and 500 MHz for the memory. With the 8 pixel pipelines this gives a maximum theoretical fill rate of 4 gigapixels a second. Just over two years ago, NVIDIA released their 5800 Ultra card in limited quantities. That card had similar fill rates and memory bandwidth to this card.

Clock speed on the AOpen 6600GT is 500 MHz for the core and 500 MHz for the memory. With the 8 pixel pipelines this gives a maximum theoretical fill rate of 4 gigapixels a second. Just over two years ago, NVIDIA released their 5800 Ultra card in limited quantities. Memory is provided by 4 32MB 2ns memory. This provides up to 16 GB of memory bandwidth, equivalent to the memory bandwidth on the 5800 Ultra, NVIDIA’s flagship card of two years ago.