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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  • Dasterdly - Saturday, October 30, 2004 - link

    Im willing to settle :p
    Also the 2 gpu on one card, or even on one chip would be good. Probably what ati should/will do now to keep up.
    I had the v2 12 mb and it was the fastest card to play my games for more than a year. After that I bought another one and was good for another year or so till the gf2 gts came.
    With the product cycles bumped up by Nv (and everyone else to compete) to 6 mo, I dont know if it would be worth it till they reach thier cap.
  • Grishnakh - Saturday, October 30, 2004 - link

    Well, Human beings seem to be preset to criticize what they just don't need.
    If you think SLI is nothing to you, that mean you just don't need these behemoths, so you will never buy nF4 SLI, KT890, etc, then SLI is nothing concerned with you.
    And Honestly, I wonder what kind of loss from nVidia can be? If you don't need it, fine, most of products meet your demand. If you need it, better! you would pay double, and so the company would earn double.
    SLI just a little like dual CPU, there always a certain population, though not much, need it
  • GhandiInstinct - Friday, October 29, 2004 - link

    Well X2 utilizes each GPU to perform half the screen making a more efficient cooperative effort than SLI. Plus you won't need to keep updating your drivers like SLI and the drivers will come straight from AlienWare.

    It's more appealing to use any combination of GPUs you want rather than SLI. So I want the best performance so I have to pay a premium to be stuck with Nvidia again? Not making that mistake again...
  • caliber fx - Friday, October 29, 2004 - link

    Wonder why alot of you are saying that the driver needs to be "specially written" for a game because even anand said that "In our conversation with NVIDIA, we noted that this technology should work with all software without any modification necessary". If you are talking about driver tweaking then even single gpu solutions are guilty of that one. The tweaks toward the nv30 or ati with their ai solution are just a few examples and I bet if the previewer had more time with the system in the right place he would have ran many other applications. I think most of you have gotten dual cores cpus mixed up with sli and I don't blame you because their are so many just introduced features that are currently not in use in alot of software like amd64, sse3, ps 3.0 and multithreading. Funny thing if their are games out there that can take advantage of all these features to the fullest I can't imagine what that would produce and the sad thing is all these features can be implemented on one machine. Also that alienware solution seems less efficient than sli.
  • GhandiInstinct - Friday, October 29, 2004 - link

    I'm sure everyone agrees that the drawback with this technology is it only supports inferior Nvidia GPUs.

    I'm looking forward to Alienware's X2 technology that combines any gpu combination at a much more efficient architecture.
  • TrogdorJW - Friday, October 29, 2004 - link

    My only question is about the small HSF on the NF4 Ultra chipset. That appears to sit directly underneath the second PCIe slot. Kind of odd, that. How difficult was it to install the cards in that board, Anand? It will also be interesting to see how performance changes over time. With their higher clock speed, I think SLI 6600GT should do better than a 6800GT. Seems like a driver optimization problem to me, although the lack of RAM might also come into play.

    And #11, what was that crap about requiring more geometry processing power to do SLI!? Do you have some reference that actually states this? Seems to me like it's just a blatant guess with not a lot of thought behind it. A card might need to do more geometry work in SLI relative to non-SLI, but twice as much? Hardly. I have a strong suspicion that the vast majority of applications do not come near to maxing out the geometry processing of current cards. Look at 6600GT vs. X700XT: 3 vertex pipelines vs. 6 vertex pipelines. Why then does the 6600GT win out in the majority of tests?
  • Reflex - Friday, October 29, 2004 - link

    #44: Why would DD encoding be a selling point? It is a compression algorithm among other things, and as a result it will degrade your sound quality. It makes sense for DVD's, but for quality PC audio it makes no sense at all. If you want multi-channel(sound on your back speakers) just use analog connections and specify in the control panel for whatever card your using that you'd like it, most give the option.

    Contrary to popular misconception, Dolby Digital, while nice for movies, is a bad thing for PC audio in general. It is one of the reasons that the SoundStorm is not considered a high end solution, despite how nVidia marketed it. Regardless, if you use a digital connection and you have a DD source(DVD movie for instance) your sound card no matter what brand will pass that signal through to your reciever and allow it to decode DD.
  • DrumBum - Friday, October 29, 2004 - link

    is it possible to run three monitors off of an SLI setup and run extended desktop across all three?

    (play a game or watch a dvd across three monitors)
  • Mrvile - Friday, October 29, 2004 - link

    Wow nVidia totally blew ATI away in Farcry (which is weird cuz Farcry is Direct3D) according to http://www.anandtech.com/video/showdoc.aspx?i=2044... benchmarks. But these are kinda old benchies, from May...
  • gplracer - Friday, October 29, 2004 - link

    I think this is a good solution for the time being. If I were going to build a new system I would want the GF4 with SLI capabilities. What if someone bought this board and one 6800 GT. Then at a later would it be impossible to buy another newer nvidia card and run it sli or would it have to be the exact same card? Also no one has noted that this sli capability is great for amd and not so good for intel. Some people will want this and intel has nothing to currently offer that I am aware of.

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