Last summer, shortly after the introduction of nVidia's 700 and 8000 series motherboard chipsets, OCIA.net took a closer look at one of their new features, Hybrid SLI. Either through augmenting graphic processing power via GeForce Boost, or reducing power consumption using Hybrid Power, nVidia combines the onboard graphics chip with a supported discrete video card to offer expanded capabilities over a more traditional multi-GPU configuration. While our testing revealed that there were advantages to this technology, albeit somewhat meager, there will surely be even more performance or savings to be had as integrated graphics processing becomes more capable and high-end discrete video cards become more power-hungry.
The one thing we didn't get to try at the time was how a more modern, traditional multi-GPU setup is capable of enhancing a system's graphical horsepower. The nVidia GT200 core cards, the GTX 260 and GTX 280, were relatively new and expensive, and frankly it just wasn't in the budget to obtain a second one for testing. Now, more than a year later, the GT200 core is still nVidia's top-dog, but the cost of entry to this level of performance has dropped significantly. With the advent of newer, faster cards such as the GTX 275 and 285, the now-lowly but revamped, die-shrunk 260 can be had for well under the $200 mark, or even less for the original 65nm, 192sp core cards.
It's one of these cards, basically identical to our original EVGA GTX 260 from last year, that we've got from the team over at Geeks.com for comparison today. Featuring a 576MHz, 192sp processing core with 896MB of 1000MHz GDDR3 linked via a 448bit interface, the EVGA 896-P3-1260 differs from our existing card only in the fact that it comes as a white-box, refurbished unit. Lacking the colorful retail box, bundled software title and flashy product information, the card still possesses all the important stuff, namely the same hardware platform needed to link the two cards via nVidia's Scalable Link Interface, or SLI.
While it's not a requirement for SLI that the cards be completely identical in manufacturer and model, it certainly doesn't hurt to match them this way. As long as the device identifier is the same, they don't even need to have the same core revision. We could have used one of the newer 55nm, 216sp GTX 260's for example. However, similar to what happens when you combine differing hard drives in a RAID array, the performance of any one of the group is limited to that of the lesser hardware. For this reason it's best to avoid mixing newer with old, or those overclocked edition cards with plain vanilla ones.
Join me as I take a look at a modern SLI implementation and see if two cards really are better than one.