Nvidia SLI: Shazbat!'Shazbat' is intended to convey excitement.
That's me. Mr. Excitement.
AnandTech tested an Nvidia nForce4 SLI (scalable link interface) system and produced the most comprehensive set of benchmark information currently available. And it's very, very good news. Link here: http://www.anandtech.com/video/showdoc.aspx?i=2258&p=1.
Briefly, if you haven't heard about this, the SLI technology makes it possible to use two graphics cards, working together, in the same system. It's not the same tech as the old Voodoo 2 SLI setup, though, and I'll discuss that in more depth later.
I had two concerns about this technology when it was originally announced: one, that the potential performance increases would be compromised by inefficient drivers, and two, that the complexity of the technology would produce graphic anomalies in rendering.
Based on AnandTech's benchmark data, my first concern (about performance) is unnecessary. At the highest resolutions, performance increases are on the order of 70% over a single-card solution. That's spectacular, to say the least.
My second concern, about rendering issues, is still something to watch. This technology doesn't use a simple, brute-force to using two graphics cards--it's not alternate frame rendering or half the screen for each card or something along those lines. Instead, there is apparently an adaptive algorithm that determines, on the fly, which of multiple methods will be used. On the plus side, that could result in much greater performance increases. On the downside, and I think this could be significant, it makes the drivers far more complex, both to create and maintain. AnandTech notes that
"Although motherboard and graphics support for SLI is definitely close to being ready, we are not so certain about the maturity of the drivers. NVIDIA's own tests were conducted under three applications: Doom 3, Halo and 3dmark 05. Although our own tests added two more benchmarks, they didn't run without their fair share of display issues."
If the display issues are resolved, then this technology is going to rock the graphics card industry, and it's noted in the article that ATI is rumored to working on some sort of SLI solution as well.