SLI Performance

For months, nVidia has been sneaking peeks at their upcoming Dual Video card capabilities, based on a technology known as SLI, or Scalable Link Interface. Not since the PCI Voodoo 2 from 3dfx in 1996 have we seen such a solution from a major graphics vendor. Of course, history saw the original 3dfx die in the market place. The single-slot AGP was introduced, 3dfx lost the video wars, and nVidia purchased what was left of 3dfx.

We have been told that 3dfx engineers had quite a bit to do with the design of the new GeForce 6 series, and that is finally starting to make sense when we see that SLI capabilities are built into the 6 series video cards. Dual AGP would require a custom design, but PCI Express, like PCI in the past, finally provides the kind of platform that nVidia needed to launch a new SLI solution.

While nVidia was not ready to ship nForce4 SLI reference boards for review, they were demonstrating a major manufacturer's nF4 SLI board with a pair of nVidia 6800 Ultra video cards at 1600x1200 resolution at 4x AA. We also got to play with the SLI system with an Athlon 64 4000+ CPU, confirming benchmarks that were supplied by nVidia.

Single GPU vs. SLI - nForce4 SLI
6600GT 6800GT 6800 Ultra
Single SLI % Increase Single SLI % Increase Single SLI % Increase
Doom3 17.3 32 85% 37.9 65.2 72% 42.4 71.7 69%
Halo 37.23 58.58 57% 50.01 72.76 45% 57.21 79.01 38%
3DMark05 3186 5698 85% 4588 8271 80% 5211 9297 78%

Increases in video performance from 38% to 85% are certainly impressive, and there are gamers and performance enthusiasts who will be flocking to the new nForce4 SLI boards as soon as they start shipping in the next few weeks. Perhaps the most impressive gain here is the performance leap with a pair of SLI 6600GT video cards. Two of these less than $200 cards are actually faster in most benchmarks compared to a single $400 6800GT. This provides an interesting upgrade path for many users. Of course, a pair of 6800GT or 6800 Ultra cards take performance to levels that we have never seen before.




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Shipping boards will allow a single video card of any brand at x16 PCIe or 2 nVidia video cards in two x8 PCIe slots in SLI mode. The SLI boards can be switched easily from x16 to SLI mode by switching a programming card on the board.



Click to enlarge.


nVidia says that the first nForce4 SLI boards will be available in the next few weeks from Asus and MSI. Other manufacturers will also be supplying SLI motherboards later this year.

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  • Zac42 - Tuesday, October 19, 2004 - link

    I think that it has to be two Nvidia cards with an SLI connector. You are thinking of the alienware video array, which theoretically can use two different branded cards.
  • GhandiInstinct - Tuesday, October 19, 2004 - link

    Wesley,

    So in SLI, I can put any two video cards together? No matter the spec difference or maker difference? New and old? Future and past?
  • microAmp - Tuesday, October 19, 2004 - link

    I take it the SLI benchmarks from nVidia were done at about 1600 x 1200 resoultion?
  • Wesley Fink - Tuesday, October 19, 2004 - link

    Kris -
    Anand and I got some hands-on time with the SLI system while we were visiting nVidia. The benchmarks we ran confirmed the numbers reported for the 6800 Ultra single and SLI. The test system was an Asus SLI motherboard with a 4000+ CPU. While we did not personally run benchmarks with the 6600GT SLI or the 6800GT SLI we have no reson to doubt nVidia's numbers based on what we did confirm.

    The Reference board is NOT SLI, which is why SLI testing was limited to our time with nVidia.
  • KristopherKubicki - Tuesday, October 19, 2004 - link

    #6 those are NVIDIA's benchmarks, not actual 3rd party confirmed benchmarks.

    Kristopher
  • Wesley Fink - Tuesday, October 19, 2004 - link

    #2 and #4 -
    SLI Performance tests are in a table on page 3. Two 6600GTs don't outperform a 6800 Ultra, but they do outperform a 6800 GT.
  • ksherman - Tuesday, October 19, 2004 - link

    #4, from what ive heard, it is probablyh likely that two 6600GTs would definetly cream the 6800 ultra. I do agree that we need some SLI benchies!!!
  • ariafrost - Tuesday, October 19, 2004 - link

    *Drool* Anyone know how much of a performance boost would come from SLI yet? I'm wondering if two 6600GTs would outperform a 6800 ultra.
  • glennpratt - Tuesday, October 19, 2004 - link

    Page 2

    "While nVidia was not ready to ship nForce4 SLI reference boards for review, they were demonstrating a major manufacturer's nF4 SLI board with a pair of nVidia 6800 Ultra video cards. We also got to play with the SLI system with an Athlon 64 4000+ CPU, confirming benchmarks that were supplied by nVidia."
  • Jincuteguy - Tuesday, October 19, 2004 - link

    why didn't anand did any SLI performance test? i thoguht this board suppose to have SLI.

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