D-I-Y SLI with DFI: Free Performance?

Article Index
D-I-Y SLI with DFI: Free Performance?
Setting up SLI on a non-SLI board
Performance Testing and Conclusion

Product(s): DFI LP UT nForce4 Ultra-D, 2x MSI NX6600GT TD128E

Disclaimer - Do not attempt this mod unless you are totally willing to kill your motherboard and possibly other components plugged into the board.  This requires soldering and should not be attempted unless you are a trained professional.  You WILL void your warranty and be up the creek without a paddle if your board dies.  That being said, it's a pretty cool mod.


Months ago when DFI released their nForce4 Ultra-D series of motherboards, some discoveries were made regarding this board.  It was common knowledge that the board had two 16x PCIe slots and a series of jumpers marked "SLI" but the chip was not capable of SLI as it was the nForce4 Ultra chipset.  Some people discovered that certain drivers would actually enable SLI operations, but nVidia quickly patched those up and "software initiated" SLI was no longer possible.

Reports varied around the web from people who claimed their board could run SLI and others that said it was impossible.  I purchased the nF4 Ultra-D for our test rig hoping that it could be modding into an SLI board, but I was quickly loosing hope.

Different guides surfaced around the web on how to hardware mod your motherboard into an SLI board and hope resurfaced.  After reading a few articles and checking out some pictures, I called Nicao and asked if he was up to soldering my motherboard.

The only fly in the ointment was that I didn't have an SLI bridge, and at the time I wanted to mod the motherboard, that was the only way to achieve SLI.  Since then, nVidia has released drivers that will SLI enable cards even if they aren't connected by the SLI bridge.  This comes at a performance hit, but at least it's available.  I'd been looking around the web for a retail SLI bridge, but the shipping cost of $20+ USD really turned me off.  I put out the plea in our forum and LobbDogg came to the rescue.  He fired off an extra SLI bridge that his dad had laying around and I got it next-day.  Holy cattle - there's a buddy for you!  Thanks.

This article is not going to discuss SLI.  We are assuming that you already have a little bit of knowledge regarding nVidia's Scalable Link Interface.  If you need to be polished up on this tech,
Anandtech does a great job explaining it in their original GeForce 6 SLI article.

The Project:

The purpose of this project and article is to see if we can take a non-SLI motherboard and turn it into an SLI motherboard.  If successful, we will also look at performance of the setup and see how single card, bridgeless SLI (driver based) and hardware based SLI compare.  On to the hacking!

Reports have shown that the only physical different between an nForce 4 Ultra and nForce 4 SLI chipset is that a single trace has been cut.  To enable SLI features, all you have to do is close the trace with a graphite pencil, conductive pen or more permanent - solder.  I'm a cheap guy, so I didn't want to go buy a conductive pen, and graphite seems a little flaky.  I called up Nicao, and asked him if he could do me a small favor.  He repairs motherboards and replaces capacitors almost on a daily basis, so I had a little faith in his ability.

I say a little, because when he actually soldered my chip, I couldn't look.  I was too nervous as this mod could easily wreck my motherboard and it definately voids your warranty.

nForce 4 Ultra Chipset
 nForce 4 Ultra Chipset

+Solder = nForce 4 SLI Chipset
+ Solder =  nForce 4 SLI Chipset

I recommend you click the above thumbnails, then click the picture that pops up again to view full size.  The chips is quite small, and it takes a steady hand to solder those points.

In reality, it took longer to set up the camera to take the above pictures than it did for Nicao to solder the contact points.  In less than a minute we were ready to fire it up and see if it would post.  We dropped in some RAM, and a killer 2MB PCI graphics card in case anything blew up.  After pluggin in the power, I fired it up and was was met with this boot screen:


I guess it really is that easy.  Wow.

On the next page we're going to look and see if Windows likes the new SLI chipset and see how to set up a SLI system for some benchmarks.