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.




Click to enlarge.


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.

The nForce4 Family ActiveArmor: nVidia Secure Networking Engine
Comments Locked

101 Comments

View All Comments

  • geogecko - Tuesday, October 19, 2004 - link

    #68

    Hmm...that search result at newegg.com pulls up 12595 results. Far to many for me to look through...

    Did you copy the link correctly?

    Thanks for the information. If the link won't work, an official part number from newegg (or vendor part number) will work for me.

    J.
  • thebluesgnr - Tuesday, October 19, 2004 - link

    I'm a little disapointed that the original article didn't say anything about sound, and that it still doesn't in the "Final words..." page. No, I don't meand SoundStorm.

    From AT's previous article on CK8-04: "Vanilla flavored CK8-04 is very much the same as nForce3 250Gb, with the addition of 7.1 high definition audio and PCI Express".

    So, they dropped the high def audio?
    If that's the case both Intel and VIA (if the information on the VT8251 is confirmed) are ahead in this area, which is, for many, much more important than some silly hardware firewall.

    In closing, I'm disapointed at AnandTech for:

    1) being excessively positive about nForce4 (no mention of lack of high def audio, no mention of any disadvantages of SLI, like higher price of the motherboard and power consumption of two cards, or lack of PCI-E x1 in that MSI mobo);

    2) completely ignoring the release of VIA K8T890 and KT880 chipsets.

    The KT880 has been out for months, there are motherboards in retail (the K7V88 in particular seems to be doing very well, given the number of user reviews and their ratings on newegg).
    Also, you reviewed the [b]nVidia[/b] nForce2 Ultra 400Gb chipset, so "socket A is dead" is not really an answer I'd understand.


  • haris - Tuesday, October 19, 2004 - link

    What's the big deal about SLI? The average increase in performance will probably be around 50-60%. That's nothing to be ashamed about, but at what cost do you get it? Two 6600's still cost almost as much as one high end card, so there is little/no cost savings. What about the power requirements and noise level. That machine has got to be a freaking monster to work/play on.
  • KristopherKubicki - Tuesday, October 19, 2004 - link

    Geogecko:

    http://www.newegg.com/app/SearchProductResult.asp?...

    Kristopher
  • mrdudesir - Tuesday, October 19, 2004 - link

    #62
    First off, each slot is an x16 slot physically but only 8x of actual bandwith. However that still means that each slot has 4GB/s of bandwith, way more than any modern cards used. There will not be any performance hit, simply because the slots have plenty of excess bandwith.
  • geogecko - Tuesday, October 19, 2004 - link

    Can I get an exact part number of the Corsair 3200XL memory you are talking about on the test platform? I've been looking for it, but I've not seeing this 3208v1.1 number anywere...

    Thanks. By the way, which memory is better, the OCZ or the Corsair?
  • knitecrow - Tuesday, October 19, 2004 - link

    All you guys about doom3 don't need hardware, should read:
    Http://www.beyond3d.com/forum/viewtopic.php?topic=14459&forum=9
    http://www.theinquirer.net/?article=17525

    Basically creative said it invented a particular 3d positioning method, Id was forced to license and support EAX HD.


    #62, Not unlike a CPU, a GPU is programmable to a certain degree. I am sure you can make it do almost anything.... but a dedicated solution will always be more efficient.



    #63 -- "A card based around the VIA Envy 24HT is all anyone needs."

    Rubbish.


    Envy24 cards do jack for 3d positional audio. If you compare a software based vs hardware based solution, the hardware based stuff (soundstorm, creative noiseblaster stuff) always win out. They are more accurate in their positioning and reproduction.
  • quanta - Tuesday, October 19, 2004 - link

    Actually, id licensed EAX HD for use with Doom 3. Even without EAX HD support, Doom 3 will just send the audio streams to DirectSound 3D engine for mixing purposes, which will take advantage of 3d audio accelerations if any.
  • PrinceGaz - Tuesday, October 19, 2004 - link

    Doom 3 doesn't use hardware accelerated sound, so SoundStorm has no benefit. If you are having problems with the sound, you might want to adjust hardware acceleration or something.

    Sound only takes a tiny amount of CPU power when you've got a processor like a 3800+ so it doesn't really matter whether or not its hardware accelerated. Its even less important when you consider that games are increasingly GPU bound, and that theres plenty of CPU power spare for processing sound. A card based around the VIA Envy 24HT is all anyone needs.
  • quanta - Tuesday, October 19, 2004 - link

    #54/57, the decision to dump dedicated SoundStorm hardware actually made a lot of sense, because NVIDIA already has a powerful VPU that can be used as an APU if the company wanted. In fact, NVIDIA can just license AVEX[1], which currently only works on NVIDIA processors, and if NVIDIA play the cards right, it can just bought the BionicFX company now/soon and keep an edge over the competitions all to itself.

    As for the SLI, I think it will be too confusing for end users, and the dual slot design will likely be short-lived. Think about it, there are only 20 PCIE lanes on nForce 4, and each video card uses 16, so at least one card only runs a fraction of the speed, crippling performance. It may be technically correct that current apps don't need all 32 lanes, but it will be tech support nightmare for video card manufacturers from users who expected full blown performance. It will be much easier to just build a 16/20/32/etc-lane PCIE video card with two VPUs in it. That way users don't have to worry about the upgrade restrictions and performance issues, and easier for video card makers to sell dual VPU products. Sure, you lose the upgradability, but without tech support problems, card makers don't have to worry about people buying fewer cards because they want to wait for cheaper, more user friendly SLI solutions.

    [1] http://www.bionicfx.com/

Log in

Don't have an account? Sign up now