Final Words

The performance advantages due to SLI are nothing to be disappointed with, using two GPUs NVIDIA is able to deliver next-generation graphics performance with today's cards. Keep in mind that our numbers were taken at relatively high resolutions with 4X AA enabled; without AA enabled and at lower resolutions the performance gains from SLI become much lower as you are far more CPU bound.

The GeForce 6600GT is the prime candidate for the SLI poster child as it is the most affordable card with SLI support from NVIDIA. Unfortunately our tests here today are more geared towards the higher end cards as the 6600GT, even in SLI mode, is still generally outperformed by a single 6800GT. At lower resolutions or with AA disabled, the performance of two 6600GTs would definitely be more similar to that of a single 6800GT. But the important thing to keep in mind here isn't what you can do with two cheaper cards and SLI, but rather the upgrade potential SLI offers. Buying a $200 6600GT today and upgrading to another one several months down the road, at a potentially much lower price, is a great way of getting the performance you want today while at the same time having a cheap upgrade path for when tomorrow's games come out.

The GeForce 6800GT in SLI mode truly skyrocketed to a new level of performance, but a very costly one. With a pair of 6800GTs selling for about the price of most users' upgrade budgets, we once again see more potential in the upgrade value of SLI rather than the initial purchase value. However, if you can afford it, a pair of 6800GTs in SLI mode will definitely offer some serious performance in all of today's games. Interestingly enough, spending close to $1000 on graphics cards still won't let you play at 1600 x 1200 with 4X AA at over 100 fps in Doom 3; but if you're willing to settle, over 60 fps is a piece of cake.

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. The complexity of the SLI driver and ensuring game compatibility is undoubtedly a major factor in the release date of SLI. We are also hearing that chipset availability is a bit on the limited side for nForce4 SLI, with most manufacturers planning on shipping boards in early 2005. ASUS and MSI both seem to be on track to a release by the end of 2004, which will definitely give them the lead if NVIDIA can get finalized drivers out in time.

All is not quiet on the ATI front though, rumor has it that they are also planning on some SLI-like solutions on both the chipset and GPU side. Given the flexibility of PCI Express to support multiple high-bandwidth slots for graphics, we would think that there's no reason (other than driver support) to not want to have SLI support within a product family. The introduction of SLI could lengthen the GPU product cycles as performance can be guaranteed for much longer, but it could also increase the expectations of upcoming GPUs like NV50 and R500. We would not be too surprised if supply issues of many of the popular SLI cards developed right before the launch of a new GPU to prevent a lackluster introduction.

In the end we're rather pleased with SLI as it promises to increase the life span of your graphics card investment, something that we've been dying to have for quite some time. We will be sure to do a full review on the final shipping SLI motherboards and GPUs when they are available, but until then we hope you've enjoyed our preview.

Very special thanks goes out to Vincent and Iris of MSI for putting themselves and their engineers through hell in order to make this review possible. You would not believe how difficult this little benchmarking opportunity was to put together :)

Far Cry Performance
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  • darkrequiem - Tuesday, November 16, 2004 - link

    What I'd really like to see is how Doom3 performs with this SLI setup running in Ultra quality mode. They recommend a 512MB card for this mode, and here we have a total of 512MB between the two cards. It'd be interresting to see how many FPS can be achieved at this quality setting.
  • MightyB - Wednesday, November 10, 2004 - link

    Hmm Im gonna wait out for the ATI solution and hope they will make it possible to use two diffferent types of cards. Would love to have the new x800 All in Wonder matched with another X-series card :-) This way I can get great performance along with the much better ATI picture quality and even TV.. :-)

    And before you flame me being a ATI fanboy.. I own a Nvidia card.. Im talking about 2D (windows desktop) and Movies when i refer to picture quality. I see now real difference in games!

    Best regards
    mightyB
  • MiLaMber - Sunday, October 31, 2004 - link

    Perhaps slightly annoying this article to those ppl who have a Geforce 6800GT, like myself, just like the fact that the NF 4 is a no go.
    Looks like a possible upgrade to PCI Express will be on teh cards in..18 months, but I see this as a good thing, better motherboards, a maturer PCI Express solution.

    Guess could always sell the 6800gt agp when the pcie version comes out though huh lol, and then start considerin SLI again and indeed NF4.
  • Reflex - Sunday, October 31, 2004 - link

    Thats his point, because each card does 50% no matter how much work a section of the screen has, it won't necessarily utilize both cards fully. If your wandering through UT2k4 and there are no vehicles in the sky, but there is a massive ground battle going on, you will see hardly any benefit from the Alienware setup, but you'd see a huge benefit from the nVidia SLI solution since it will give the card rendering the top half of the screen more to do rather than sitting idle.

    Believe what you want, but I have a bad feeling that the Alienware tech will never actually appear on the market. It was announced months ago, and now if it arrived it would more or less be an Ati only solution, since if you had nVidia cards you can do SLI natively without Alienware's technology(and nVidia's solution should be faster most of the time). It was a good attempt by them, but at this point its not worth pursuing.
  • GhandiInstinct - Sunday, October 31, 2004 - link

    Swaid: Your ratios are a bit off, did you see the E3 demonstration? Maybe you should have another look at it. The ratio is always 50/50 even if the lower or upper half has a bit more work to be done, the thing is its only half the screen, resolution. Making the cards work a lot less than if they were single. Never the less, it's always seamless no matter how high your graphics settings.

    Ever heard of frame locking? Frame locking synchronizes display refresh and buffer swaps across multiple cards, preventing visual artifacts and ensuring image continuity in multi-monitor (or multiple video card) applications like simulations.
  • Reflex - Sunday, October 31, 2004 - link

    Hell, I'm an anti-nVidia guy and I still recognize this as a nice deal for those of us who'd love a cheap way to upgrade in the future when a secondary card will be cheap.

    I still won't be buying it however, the 2D performance of nVidia solutions is still crap at high res, and I spend a lot more time in front of a web browser than I do in front of games. But since Civ3 is the most recent game I have purchased, I don't imagine its really much of an issue for me. A Parhelia would meet my gaming needs just fine. ;)
  • Swaid - Sunday, October 31, 2004 - link

    GhandiInstinct,
    His logic is correct, while your's on the other hand needs to be double checked. In your case (X2/Video Array), we can take the an example of a situation where the upper half of the screen has a more complex scene (or more activity) going on, thus making Card 1 (video card rendering the upper half) work at 100% while Card 2 (video card rendering the bottom half) only needs to work at 80% to keep up with Card 1. Thats not an efficient solution. This is where SLI's technology can really shine. If you take that same scene thats being played through and use SLI, Card 1 will now render the upper 40% while Card 2 will render the bottom 60% and this would keep the 2 GPU's at 100% load. Now that is an efficient solution. That senario can pretty much go for all FPS games. Dynamic load balancing appears to be a better 'logical' solution. But I am willing to bet that you are an ATI fan or maybe it has to do with some sort of loyalty towards Alienware, so SLI is feeling you left behind, thus your unwillingness for reason. There are many articles that try and explain the whole situation with SLI.
  • Zebo - Sunday, October 31, 2004 - link

    Oh and thanks Anand for this exclusive. I'm with the camp which says "single card" and "frequent upgrades" only because of noise, heat, power and very low resale when I'm finally done with the two cards.
  • Zebo - Sunday, October 31, 2004 - link

    More options are always a good thing. How can anyone be down on this tech is beyond me.
  • GhandiInstinct - Saturday, October 30, 2004 - link

    SLI requires special circuitry to be incorporated into GPUs and, for extra speed gain, into core-logic. Alienware’s Video Array technology does not require any special logic to be incorporated into graphics or system chips.

    This makes it less of a driver prone problem than SLI.

    Over.

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