The first SLI technology released into the mainstream was the 3Dfx Voodoo2 series back in 1998. While the semantics have changed from "Scan Line Interleave" (3Dfx) to "Scalable Link Interface" from Nvidia, the fundamentals are largely the same, involving disseminating graphics-intensive algorithms between multiple GPUs. This allows the integration of multiple cards into one system to take advantage of load balancing to increase frame rates. However, Nvidia's SLI usually comes at a small price premium, so we've tried to take a crack at an unapproved "GLI" solution from Epox to see if the numbers can match those churned out by SLI systems.
Some of the best eye candy in today's games - think of high dynamic range lighting and anti-aliasing - is very GPU-intensive and causes a drastic performance hit when enabled. To further address performance issues, Nvidia is now bandying about quad processing solutions. Its latest graphics solution allows consumers to install two GeForce 7950 GX2 cards, each with two processors, into an SLI system." Bear in mind the drivers are still in beta, but you can check the system out at Beta Driver for Quad NVIDIA SLI Technology or read our latest story Get Quad SLI Before It Is Hatched.
However, quad graphics is not required for a great gaming experience. In fact, even low-budget SLI solutions allow gamers to experience better frame rates, increased realism and faster response time without breaking the bank. Running SLI on a non-certified motherboard certainly is the cheapest way to get SLI to work.