Breaking the SLI "Code"

With the flood of nForce4 motherboards getting ready to enter the market, we had a decent selection of very recent nForce4 Ultra and nForce4 SLI motherboards. We also had both the SLI and the Ultra versions of the DFI based on the same PCB. With this wide selection of boards, we could look at the differences in the Ultra and SLI chipset and also confirm that they were not unique in any way.



If you look closely at the pictures of the SLI and Ultra, you will see that the chipset themselves appear identical. However, a closer look at the resistors and pads surrounding the chip shows some differences. The resistors appear the same on both, but there are 3 sets of resistor pads that are closed on the SLI chipset while just two sets are closed on Ultra. The vertical set of resistor pads just to the right edge of the chip itself is closed on SLI and open on Ultra. We could find no other obvious differences in the 2 chipsets. Could it be this simple?

We closed the set of resistor pads on the DFI LANParty UT nF4 Ultra-D with conductive paint, as you can see in the photo below.


We set the jumpers to SLI, attached the top bridge from an SLI board, since the Ultra boards do not ship with an SLI bridge, and fired up the system. The system was immediately recognized as an SLI chipset on boot and in Windows XP by our latest 71.40 Forceware drivers. Our little bit of very easy modification had "turned" the Ultra chipset into SLI. We no longer had driver limitations and performance was now exactly the same as the performance that we achieved with a normal SLI chipset.

We also tried modifying an Ultra to SLI with an ordinary #2 pencil. It worked perfectly, and with there being so much room around the set of resistor pads, you don't have to be that neat. If you close the pads, you have converted the Ultra to SLI. Those of you who remember Athlon XP modding for CPU speed will recall how close the sets of pads were in that mod. This required masking and careful painting of the pads to be closed. With the Ultra to SLI mod, there is huge real estate around the resistor on which you are working. As a result, even "all thumbs" modders should have an easy time with this one.

Index Performance: x16 vs. x16/x2 vs. x8/x8 (SLI)
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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.
    Reply
  • 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. Reply
  • 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.
    Reply
  • 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.
    Reply
  • 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: http://www.pcper.com/article.php?aid=99&type=e...

    2) Maybe the nForce4 and nForce4-4X can be modded to add SATAII and the other features of the Ultra chipset?
    Reply
  • 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. Reply
  • 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.
    Reply
  • 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. Reply
  • 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 ;)
    Reply
  • 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. Reply

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