Date:
Sunday , June 27, 2004
Author:
Brent Justice
Editor:
Kyle Bennett
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NVIDIA SLI

It’s back! NVIDIA is re-introducing multiple video card 3D acceleration, and it may just change your mind on your next video card purchase.

Introduction:

SLI (Scan Line Interleaving) created by 3dfx six years ago was all about pure performance and higher resolutions. Back in those days whoever had the fastest graphics solution won. The idea was that if you could add multiple 3D accelerators in one system you could speed up 3D rendering on that PC. 3dfx conquered this challenge by creating SLI or Scan Line Interleaving technology. SLI technology from 3dfx worked by having one card render the even number of lines on the screen while the other card worked on the odd number of lines. This basically "doubled" frame rate performance and allowed resolutions up to 1024x768.

This SLI technology was introduced on their Voodoo2 line of video cards. The Voodoo2 was a 3D only accelerator and required that a 2D video card already be installed in the system. With SLI technology not only could you add one Voodoo2 3D accelerator, but you could add two to your system. You connected the two cards via an internal ribbon cable as well as an external pass-through cable. Once the drivers were installed it did everything “automagically”. All you had to do was sit back and enjoy much faster frame rates in your games.

At that time the PCI bus was the fastest add-in-board connection on the PC. It was because of PCI, and the multiple PCI connectors on each motherboard, that would allow for this technology to materialize. You see, once AGP was released there was only one AGP port per motherboard, so SLI technology in multiple card form was out of the question.

As time progressed PCI video cards were traded in for AGP video cards which worked on the new AGP port. This led to 3dfx creating video cards with multiple cores on one PCB ala the Voodoo5 series. It was basically like having SLI on a single board since multiple video cards were now not possible with AGP. While 3dfx went on to successfully make multiple cores on one PCB work, other companies such as NVIDIA, remained vigilant that single cores were all that were needed. Of course we know who won that battle.

ATI also dabbled in a multiple core AGP video card, known as the ATI Rage Fury MAXX. Its impact in the market place was less than memorable, as you likely don't remember them ever being for sale.

As time moved on 3dfx met its fate and shut the doors on their business. NVIDIA purchased 3dfx's intellectual properties and now it seems they are ready to reveal to us a little something they may have learned from 3dfx that is built in to their new GeForce 6 series of GPUs. And that is a new "SLI" technology.