If you have been following the news, some very strange things are going on with the nVidia nForce4 chipsets. About six weeks ago, MSI showed an nForce4 ULTRA motherboard with a regular x16 PCIe slot, plus an open-ended x4 PCIe slot. Those who saw the demos said that MSI was running two matched video cards in what they called a "semi-SLI mode", which ran at about 90% of the performance of normal nVidia SLI. This was an interesting development because nF4 Ultra chipsets are cheaper than nF4 SLI chipsets. The boards based on the Ultra chipset are, therefore, much cheaper than the high-end SLI parts that we are seeing in the market. An arrangement like this would be a god-send for computer enthusiasts who watch their budget, yet still like to enjoy most of the benefits of SLI dual video-card performance.

Just as quickly, we learned that nVidia was not happy with this "SLI hack" and they changed their drivers quickly so that "semi-SLI would not work with current and later Forceware drivers." It appears that the later Forceware drivers check the chipset ID and if the driver sees "Ultra", then SLI is not enabled. MSI decided to kill the "semi-SLI" board because it would be a nightmare supporting a board that would only run with older nVidia SLI drivers.

Then, at CES, DFI was displaying both nForce4 SLI and nForce4 Ultra motherboards with two x16 PCIe slots. We were told that Epox also had an nForce4 Ultra motherboard with another semi-SLI solution based on the cheaper Ultra chipset. DFI told us that they used the same PCB for both versions of the nForce4 boards for economy, and that in fact, the nForce4 Ultra board could run a dual x2 video mode with earlier nVidia Forceware drivers in addition to standard single x16 video mode. Given AnandTech's close working relationship with DFI, we had arranged an exclusive look at both DFI boards. When the boards arrived, we were indeed able to run an x16/x2 dual video mode on the nForce4 Ultra with driver version 66.75 - a very early nVidia SLI driver. We tried many, many Forceware versions and also found that 70.41 also worked by adding one line to the registry. However, like MSI, the Ultra dual-video only worked on very old SLI drivers or on drivers with a Registry mod.

It was clear at this point that this Ultra dual-video solution did work, but that nVidia had turned it off in recent drivers. This caused us to wonder what was really going on with nForce4 chipsets. If nVidia could enable/disable this Ultra SLI in drivers, then the base chips must be very, very similar. In fact, it would be logical if the nF4 Ultra and nF4 SLI were exactly the same chip with some modification, making the chip an Ultra in one case and an SLI in another. The pin-out configurations are, after all, exactly the same with both chipsets.

It was with this idea that we took a closer look into the possibilities, and what we found will surprise you! It turns out that the nForce4 Ultra is apparently just an nForce4 SLI with SLI turned off. What is even more important is that we also found a way to turn on the disabled SLI!

Breaking the SLI "Code"
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  • PrinceGaz - Friday, January 21, 2005 - link

    What gets me is that SLI is still viewed by so many people as a "cheap upgrade path" for their graphics later on, and they use that to justify and SLI (or possibly a modded Ultra board).

    Has everyone who comments here forgotten that there is the option of selling your 6600GT when you fancy an upgrade, and buying a second-hand 6800GT to replace it? I think you'd find the upgrade cost from the 6600GT to 6800GT would be less than a new 6600GT would cost you, regardless of how much prices on new cards fall. The 6800GT will also outperform two 6600GTs in almost all games, especially at higher resolutions and quality settings.

    Even if the second-hand price difference between the 6600GT you want to sell, and the 6800GT you'd want to buy isn't smaller than the cost of a new 6600GT; there's still the question of what are you going to do with two outdated 6600GTs when it's time to do a proper upgrade. Single 6600GT cards will be going dirt cheap because they'll be considered low-end, and nobody would buy two of them when much better single card solutions are available. A 6800GT will at least have some reasonable second-hand value still.

    The only possible reason for seeing SLI as a viable upgrade option is if you're afraid of buying or selling stuff second-hand. In that case you're missing out on a lot of bargains.

    SLI should only be considered by people buying 6800's, either both of them at once or the second within a few months. Considering the cost involved, they'd be fools to save a few dollars and hope the Ultra->SLI mobo hack works correctly for them.
  • crash - Friday, January 21, 2005 - link

    #73 and it will all be moot because you won't have the bridge connector. You will either have to make your own or buy one from someone else. Either way, the cost will reach or exceed what you would've spent had you purchased the SLI board in the first place.
  • AtaStrumf - Friday, January 21, 2005 - link

    Some people still don't get the point of SLi. It's in the cheap, gradual upgrade path.

    This hack, if nVidia doesn't disable it -- driver support in case of SLi is extremely important - new games will require new drivers!!!, makes this an even better deal for the cheap bastards among us, because you only pay a slight premium for being able to cheaply uprage later on (66(8)00GT will be much cheaper when I buy a second one) instead of having to first cash out big time for an SLi mobo just to get into the SLi game.
  • MarkM - Thursday, January 20, 2005 - link

    #65, #66 - what is wrong with nVidia marketing different performance levels. Why do you feel you need to single them out for your wrath? Do you think the CD/DVD for Microsoft's OfficePro costs any more to burn than the one for their OfficeStanderd? Do you get mad at AMD preventing you from increasing the multiplier on their A64 chips?

    Sheez, it's a common buriness practice, everyone does it. If it let them lower their unit cost by producing both chipsets on the same line instead of needing different ones, then bully for them.
  • ChineseDemocracyGNR - Thursday, January 20, 2005 - link

    #63, I don't think you will be able to buy the 3D1 card without Gigabyte's SLI motherboard.

    I have two comments:
    1) in your future benchmarks of SLI products could you add some games that may not have been optimized by nVidia? I don't think most people know about this:

    2) Maybe the nForce4 and nForce4-4X can be modded to add SATAII and the other features of the Ultra chipset?
  • bupkus - Thursday, January 20, 2005 - link

    #69 - My only suggestion is if you see the SLI board price as just too high for the initial introduction, the price drop over the next year will subsidise your next upgrade assuming it will be atleast a year until you go for a new video card. Of course what will be is just a guess.
  • OriginalReaper - Thursday, January 20, 2005 - link

    It's already $800-1000 on the 2x GPUs, I think spending a little extra for a the nV SLI x8/x8 is worth it over the Ultra SLI.

    Not that I'd want either solution at the moment.
  • bupkus - Thursday, January 20, 2005 - link

    Consider also, you can buy an SLI capable display adapter today with a non-SLI motherboard. In a year when you may want to upgrade your video by buying a twin you may also be considering a new, dual core CPU.
  • Live - Thursday, January 20, 2005 - link

    To all of you who does not see the point of this mod:

    The point as I see it is not to buy 2 * 400$ cards and then skimp on the motherboard. This is for the ones who can’t afford SLI today. Buy this motherboard and your SLI ready if and when cheaper cards are out or your preferences/financial situation changes.

    I'm one of those people that hold on to my parts for at least 2 years. So it’s nice to know I have as many options in the future open to me with a board like this.

    My bet is that SLI with dual core CPUs and games that are multithreaded and SLI ready from the get go like perhaps Unreal 3 or Far Cry 2 will make SLI look rather tempting.

    Imagine playing Duke Nukem Forever which will come ...heh never mind ;)
  • bupkus - Thursday, January 20, 2005 - link

    #65 - Tell nVidia to "stuff it" and wait for the X800XL. Look people, we all did just fine before SLI and we can do fine without it. Corporations just love it when we are so convinced that we need something they sell that we call them names for taking advantage. Just don't buy into it.

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