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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  • Dmitheon - Tuesday, January 18, 2005 - link

    Kudos to Wesley and the rest of Anandtech for finding this neat little hack. I wish nVidia simply didn't have the Ultra line of boards, and let the economy of scale bring the SLI board down. I'd love to see the amount of money that went into taking SLI down a notch so they could market a less expensive chipset that costs nearly the same to produce. Personally, I'll end up buying an SLI board as more hit the market and competition brings the price down from it's current $190s (just checked Why spend extra? The piece of mind that comes from knowing that nVidia is not trying to take a feature I want, away from me. To paraphrase a hookey old public service announcement: "SLi, it's not a right, it's a privledge" ;)
  • bersl2 - Tuesday, January 18, 2005 - link

    I'd rather that more nforce4 boards actually *get* to retail in the first place. Some of us don't want an SLI board (yet)...
  • Jahara - Tuesday, January 18, 2005 - link

    I'm confused. Doesn't the SLI crossover chip only come with SLI enabled motherboards?
  • Crassus - Tuesday, January 18, 2005 - link

    Does that mean that you could use any Ultra-mainboard with only one PCIe slot and run the Gigabyte 2-chip-6600GT in there with that mod?
  • Neo_Geo - Tuesday, January 18, 2005 - link

    Yep, reminds me of the GeForce/Quadro hacking possibilities.

    Hopefully, nvidia will just eventually merge the Ultra and SLI into one product.

    In the case of the GeForce/Quadro, they came out with some updated drivers to discourage hacking. Then, when that was figured out, they went a little deeper and physically changed the cores. Now, a software hack is not totally possible on GeForce (I say not totally, because the hack does partially work and gives a geforce most quadro features, but not all).
  • Wesley Fink - Tuesday, January 18, 2005 - link

    #16 -
    The DFI LANParty UT (Ultra chipset) will sell for about $140 and it can be modded to SLI. The full DFI SLI-DR will sell for about $200. There are Ultra chipset boards that sell for even less than $140, but we don't know yet if they can work as modded SLI yet - and most don't have dual video slots. There are also some very high end SLI baords that sell in the $250 to $300 range.
  • PetesEscapade - Tuesday, January 18, 2005 - link

    Helps to put something in.....

    I love it. Regardless of nVIDIA's motives, or lack thereof, it is great to see people digging, tweaking, and passing the info along to the rest of us to do with what we will.


    Why did man climb Mount Everest? Because it's there. Why try to turn a nForce4 Ultra into a nForce4 SLI? Because it's there!
  • PetesEscapade - Tuesday, January 18, 2005 - link

  • bupkus - Tuesday, January 18, 2005 - link

    Of course ATI is rushing SLI solution video cards for the nForce4 SLI and now Ultra chipsets. My guess would be their drivers will attempt to exploit the Ultra hack, unless legal advises not. nVidia understanding this and seeing their dilemma of more chipsets vs. more video cards will choose both and rush an nForce4 Ultra version 1.1. If not, ATI's SLIs will force nVidia to allow the hack in their drivers. Could an ATI chipset with a cheaper ATI SLI design open the door for ATI's chipsets?
    Hehe, lets wait and see.
  • skunkbuster - Tuesday, January 18, 2005 - link

    i wouldn't call $229 cheap. still pretty expensive to me

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