What is the nVidia SLI?

SLI means Scalable Link Interface and it is a brand name for a multi-GPU solution used by Nvidia for linking multiple video cards together to generate only one output. SLI is an system of parallel processing for graphics, designed to increase the multi-processing power available for graphics.

Sli system wasn’t designed by nVidia engeneers. The name SLI was first used by company called 3dfx - former leader in graphic cards, it was famous for creating the very effective graphic accelerator , based on chip called “Voodoo”. Voodoo was ruleing all over the world. I remember my first diamond monster graphic card with voodoo chipset - it was world first graphic card that was an appard module to primary graphic card, it was called graphic accelerator,. It’s performance for those days was magnificent. It was the beggining af this technology. 3dfx relesed it under the full name Scan-Line Interleave, which was introduced to the consumer market in 1998 and used in the Voodoo2 line of video cards. After buying out 3dfx, Nvidia acquired the technology but did not use it. Nvidia company re-released the SLI name in 2004 and intended for it to be used in modern computer systems based on the PCI Express (PCIe) bus - whitch is actual fastest graphic interface. However, the technology behind the name SLI has changed dramatically. That’s how looks the double Geforce 9800 gt cards connected with nVidia SLI system:

Soon I’ll write about SLi performance and I’ll try to answer the question: Do she SLI really doubles performance with two card connected? Is it worth to buy single better more expensive card or two weaker cards set in SLI mode?