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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  • HystericPoison - Thursday, October 13, 2005 - link

    i did the mod last night. it took me 2 tries, because i guess on the newer boards they have a dot of glue over the resistors that i had to scrape off with a knife. a dot of conductive pen (purchased at radio shack for $13 and change) was all it took. Reply
  • rancidmonkey - Saturday, February 26, 2005 - link

    Hi,
    This is my first post to Anandtech. :) I have ordered a DFI LanParty NF4 Ultra-D from Newegg, and this "SLI-enable" mod is exciting, mostly because of the "budget-minded gamer future upgrade" benefit mentioned by a couple others here. However, what do you all think of possible compatibility issues arising from attempting to pair a 6600GT purchased this month with one purchased 10 or 11 months from now? Could imperceptible changes in the manufacturing process make two seemingly identical cards not work together in SLI mode? I suppose if you really are budget-minded, you could scour ebay for a second-hand card purchased around the same time as yours.
    What do you think?
    Reply
  • cyburzaki - Thursday, February 24, 2005 - link

    please forgive me if my above comment about PCCaseGear and the bridge was already covered here. I am in a rush and only read the last fourth of posts... Reply
  • cyburzaki - Thursday, February 24, 2005 - link

    DFI sized bridges are definitely being made by at least one third-party, since PCCaseGear in Australia includes with their Ultra-D boards an SLI bridge. But I emailed them and asked them the name of the German company that makes them, and they refused to tell me.

    http://www.pccasegear.com/prod1847.htm
    Reply
  • cyburzaki - Thursday, February 24, 2005 - link

    Reply
  • LX - Friday, February 11, 2005 - link

    Wesley (or anyone else, for that matter),

    Where can one get the SLI bridge to use with this mod?

    Thank you!
    Reply
  • ImJacksAmygdala - Monday, January 24, 2005 - link

    I bet it is easier to get the SLI bridge for this mod than it is to get an Nforce4 Ultra to try it. Reply
  • Wesley Fink - Saturday, January 22, 2005 - link

    #77 - DFI tells us all boards that will reach the retail market will have the modifications we are expecting. There is a new BIOS and several updates of components to improve performance and memory compatability. These changes have been made to production boards and the first boards off the line are also being updated post-production before release to the retail market.
    Reply
  • ChineseDemocracyGNR - Saturday, January 22, 2005 - link

    By post-production modifications, do you mean that the first boards to hit the market will not have these improvements?
    Reply
  • Wesley Fink - Saturday, January 22, 2005 - link

    ALL -
    As a result of feedback to DFI on the initial testing, DFI is making a few post-production modifications to the board and BIOS to further improve memory compatability and overclocking. There is nothing wrong with current overclocking performance, but we want to bring you a review of the final production board, so we are waiting for the boards with modifiactaions to arrive. Those are expected by the middle of next week. We should have a review of both the DFI boards around the end of next week unless there are further delays.

    Reply

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