Several weeks have passed since we first began our analysis of NVIDIA’s new generation of DirectX 10 video cards. Launched on November 8, 2006, the GeForce 8 series have become the leading performers out of all single GPU solutions, NVIDIA and ATI alike, available for retail. Today our analysis will center on multi-GPU configurations of the GTX and GTS models of the 8800 series. At the present moment, these are the only video cards available that support Microsoft DirectX 10.

This means that these two video cards, along with ATI’s concurrent solutions based on the as of yet unannounced Radeon R600 GPUs, will be able to take advantage of game titles based on DirectX 10 immediately when they are released. DirectX 10 based video games are expected to start appearing on the market in the next couple of months. Although developers are enthusiastic about the new features that will be made available in the new API, their enthusiasm is restricted due to the fact that DirectX 10 is Vista exclusive. Windows XP is currently the dominant OS on the market and it will take time for consumers to transition to Vista creating problems for developers. They could either risk losing sales by developing their game exclusively for DirectX 10, or they might opt upon sticking to the existing Windows XP user base and not supporting DX10.

For the past two years nearly all high-end solutions introduced by NVIDIA have supported SLI technology. This holds true for the 88000 GTS and GTX. In SLI, consumers are allowed to connect two 8800 video cards that are the same models. It is not required, however, to have the video cards be produced from the same manufacturer.

The following table displays the technical specifications for high-end video cards from NVIDIA and ATI running in single or multi-GPU mode:

In order to support DirectX 10, NVIDIA had to create a new architecture that was radically different compared to older architectures. Thus the G80 came into existence. One of the largest architectural changes is the use of unified shaders. Because of unified shaders, there are no longer any dedicated pixel and vertex shaders. Instead, unified shaders are able to work on physics, geometry, vertex, or pixel shading depending on the task at hand.

In the course of this article we have used all 4 new GeForce 8800 GTS and GTX cards. The manufacturers of these cards are Foxconn, Gainward, and XFX. As you will see, these cards are all designed similar to each other, save for a few aesthetical changes primarily on the cooling solution, since they are all based on the same NVIDIA reference design.

Our main focus in this article is to test the performance of the 8800 GTS and GTX have under SLI. We will use a combination of synthetic tests, gaming tests, and power consumption tests in order to give you a better understanding of what to expect using SLI with the G80 architecture.