Nvidia unveils speedy 3D graphics cards

Nvidia revealed its latest high-powered graphics technology on Wednesday in front of a crowd of several hundred boisterous gamers in California.

The new GeForce 8800 graphics cards can allocate processing power as needed to create strikingly realistic 3D images. Several gaming PC companies, including Alienware and Velocity Micro, have announced plans to carry the 8800 graphics cards in their systems.

Nvidia's new graphics cards will help PCs deal with a wave of graphics-intensive applications arriving in 2007. Among those will be the Aero graphics technology in Microsoft's Windows Vista operating system, high-definition video and the DirectX10 application programming interface, said Jen-Hsun Huang, president and chief executive officer of Nvidia.

Computer graphics are currently created through a series of processing steps, explained Ujesh Desai, general manager of Nvidia's desktop GPU business. In a basic example, the chip draws the outline of an image (vertex shading), then fills in the colour shading to finish off the image, a process known as pixel shading.

The problem with this approach is that some images have complex shapes but relatively simple colouring, yet the number of transistors dedicated to either vertex shading or pixel shading is fixed. In this example, the transistors dedicated to pixel shading have to sit idle while waiting for the vertex shader to finish its task.

Nvidia's unified shader architecture allows the graphics processor to use some of the idle transistors that were previously dedicated to pixel shading to help with the vertex shading. It works the other way, too, so that if an image is relatively simple but colourful, the vertex shading transistors can switch over to pixel shading. This should dramatically improve the overall graphics performance of PCs with the GeForce 8800 cards, Desai said.

The GeForce 8800GTX and 8800 GTS are the first graphics cards to use the new technology, and they are available immediately, Desai said. The GTX costs $599 (£294) in the US, while the GTS costs $449 (£235) and offers slightly less performance.