Many that have seen the progress of PC 3D graphics over the years will remember Voodoo 2 and its dual board "SLI" capabilities. NVIDIA announced their own take on SLI in 2004 allowing users to couple two GeForce 6 PCI Express boards together in order to double the rendering potential, and now SLI platform hardware and graphics boards are in full availability.

In this article Beyond3D takes a good look at this new form of SLI, first recapping over some of the previous multi-graphics solutions, looking at NVIDIA's SLI and the modes it operates in as well as some of the issues that have to be tackled with parallel discrete graphics processing. On top of this we'll also look at the performances from examples of all the currently available SLI capable boards: 6600 GT, 6800, 6800 GT and 6800 Ultra.

"A simple implementation that just splits the rendering across two processors with one rendering an upper portion of the screen and the other rendering the rest is likely to suffer the worst with uneven workloads, and a straight 50/50 distribution is not likely to be the best solution - indeed the Metabyte solution mentioned earlier hard coded an uneven split between the two graphics boards in the system. NVIDIA's Split Frame Rendering (SFR) mode addresses this issue by altering the number of lines each of the two boards rendering on a per frame basis."