DFI LanParty NFII Ultra B Voltmods

The DFI LanParty NFII Ultra B is said to be the best NForce2 based motherboard (or even the best Socket-A board overall).
It has all the features that lots of enthusiasts all around the world were dreaming of seeing packed into one (nearly) perfect motherboard. Those massive advantages are responsible for the excellent reputation of this mainboard, but for some of the users out there this motherboard is not extreme enough, yet. Those users always try to make the best even better, by modding it, thus it matches all their needs (i.e. extreme voltages and extreme stability).
I wrote up a little guide which describes all of the mods for the DFI Lanparty motherboard (and the DFI Infinity NFII, as the layout is the same).

Required parts

At first, I'll list the parts that I used:

• one 50K (trimmer-) potentiometer for the VCore-Mod
• one 50K (trimmer-) potentiometer for the OVP-Mod (overVoltage Protection)
• one 50K (trimmer-) potentiometer for the VDD-Mod
• one 100K (trimmer-) potentiometer for the VDimm-Mod
• one 50K (trimmer-) potentiometer for the Southbridge-VMod
• three SMD/SMT 4.7K resistors (size 0805) for the VDroop-Mod
• a good soldering iron (Ersa 25W in my case)
• rosin core solder and solder flux (for example "colophony")
• some cables (I used 1mm diameter cabling, made from copper strands, normally used for hifi systems)
• some heatshrink tubing and hotglue
• and perhaps some isolating protection lacquer
• heatsinks and thermal epoxy (an alternative to the thermal epoxy would be to buy 5-minute two component epoxy and then mix that with a thermal compound; I used that and it's working fine)

First, cut off or break off one of the two outer legs of all potentiometers, because only two contacts are needed [the middle contact (signal) and one of the outer two pins (ground)]. The third one is useless and could be in your way while working on the other two legs, or could interfere with some parts on the mobo.

Afterwards, adjust the potentiometers for VCore-, OVP-, VDimm- and VDD-Mod to the maximum resistance. The potentiometer for the Southbridge-VMod needs to be set to ZERO Ohms because that Mod leads to increased voltage with increased resistance, in contrast to the other mods. Those are the values to start with - they are very important!

VCore-Mod

Datasheet of the chip:

http://www.intersil.com/data/fn/fn4765.pdf

Connect the middle pin of the 50K potentiometer to Pin #7 (FB) of the HIP6301 chip and then connect the outer pin of the potentiometer to Ground.
Pin #9 of the HIP6301 is a Ground pin, but we will need to solder a cable to the next Pin #10 for the OVP-Mod. I didn't like the idea of soldering two cables right next to each other. That would've been very hard, and why do it the hard way, if there's an easier way right around the corner. For Ground I just used the Ground point from a left-empty solder-pad ("EC18"), where DFI had planned to put a capacitor, but cancelled that idea obviously (solder point in the area that is marked white, is GROUND). Use that point as Ground for both the VCore- and the OVP-mod, it will have no negative impact on the mods.

OVP-Mod

Same chip, so no new datasheet link needed (still HIP6301).

The OverVoltage Protection-Mod is only needed, if you are going to run a VCore higher than 2.0V.
As I already mentioned above, the OVP-Mod involves connecting a 50K potentiometer from Pin #10 of the HIP6301 chip to Ground.
Just connect the outer pin of the potentiometer to the Ground point mentioned above (left-empty solder-pad, not far from the HIP6301 chip). Then connect the middle pin of the pot to Pin #10 (VSEN). Well, that's it and you've finished the VCore and OVP mods.

Picture for both VCore- and OVP-Mod

VDroop-Mod

As many of you already know, the DFI board has some quite high VCore fluctuations under load. That's why some smart guys figured out a VDroop-Mod for this board, to reduce those fluctuations.
This mod is rather delicate as you need to remove 3 SMD/SMT resistors on the board in a cramped area and replace them by SMD/SMT resistors of different values.
The resistors, marked in the pic, need to be removed and then you solder in one of the SMD/SMT 4.7K resistors in each of the marked locations.
I'd advise you to order more than just the three needed resistors, as you may need to try that mod more than once before you succeed. Sometimes one or two resistors get damaged (due to overheating or whatever), so be sure to have a replacement!

VDD-Mod

Datasheet of the chip:

http://www.national.com/ds/LM/LM158.pdf

Connect the middle pin of the 50K potentiometer to Pin #6 (Inverting Input B) of the LM358 chip. Then connect the potentiometer's outer contact to Pin #4 (Ground/GND).
The measuring point for VDD is located in the top right corner of the pic. It's the right leg of the VDD mosfet.

VDimm-Mod

Datasheet of the chip:

http://www.semtech.com/pdf/sc2616.pdf

The middle pin of the 100K potentiometer normally would need to be connected to SC2616's Pin #1 (FB). But as the chip has very tiny legs/contacts, that would be nearly impossible to do with normal equipment. Thus we trace pin #1 to a SMD/SMT resistor just next to the chip (marked in the pic). Now you need to connect the potentiometer's middle pin to the side of that resistor, facing the greenish capacitor next to it, as seen in the pic. After that you have to connect the outer pin of the potentiomter to Ground. Just like when doing the VCore-/OVP-Mod, I used an empty solder pad ("EC57") as Ground. Again, it was planned to be used for a cap and was then left empty in the final product (see the pic for details). Measuring point for Vdimm is on the second mosfet from the left, under the RAM slots. Make sure to take a look at the pic for the correct leg, as it depends on how your board is placed on the table. That way, you can't go wrong.

Southbridge-VMod

For that last mod, again a 50K poti is needed. To supply more voltage to the southbridge chipset, it's required to remove the SMD/SMT resistor "R151", next to "VR4" (looking like a mosfet, right next to the second PCI slot, counting from the top). You just desolder that resistor and connect the upper solder-point, which is now empty (after having removed the SMD/SMT resitor), to the middle pin of the 50K potentiometer. Afterwards, you connect the outer pin of the potentiometer to a Ground point nearby. I used the solder-pad ("EC32") next to the battery, right under PCI-slot #3.
The measuring point for the southbridge voltage is the upper contact of the capacitor "EC42", right next to the other soldering-points.

Overview & additional modifications

That's all the info needed to do the mods!

I did the following additional modifications to my board:

• lots of heatsinks on all kinds of chips on the board. VERY important: Provide some cooling for the SC2616 VDimm regulation chip and the VDD-Mosfet, as they get extremely hot (~70°C or more; burnt my finger on those). I cut up lots of heatsinks (mostly old P1 50x50x15mm sinks which can be aquired for only a few cents today) and used thermal epoxy to put them on. I only screwed down the northbridge heatsink.




• additional cabling to connect a second PSU. One cable for PS-ON (green cable on the PSU) and one for Ground (black cable on PSU). This makes a second PSU, connected to those two cables, turn on exactly at the same time as the main PSU.




• Northbridge and Southbridge were lapped and I put heatsinks on all those chips that I thought would benefit from it. I first lapped the heatsink base, and then put sandpaper on the bottom of those heatsinks with double-sided tape. Then I sanded the chipsets with the prepared heatsink, until it was flat, i.e. the print on the chip was fully gone and it was flat to the eye.






• additional capacitors on the backside of the motherboard. Those provide higher stability on high overclocks. BUT, be sure to use LOW ESR caps (or at least 105°C rated caps), keep the leads/cables as short as possible when soldering them in and don't use too much of them. Some additional caps can help, but too many will hurt.

I've got to thank Lastviking and all the other members of the xtremesystems.org forums (and anyone else involved) who helped in developing all those mods! Without their help it would have been much much harder to write this article.
Lastviking's "DFI Lanparty & Infinity FAQ" on the xtremesystems.org forums already includes nearly all of the mods that I described in the text above, so head on over there to view the original if you want. My goal was to make a guide with better and of course more pics, thus making it easier for you to follow. I hope I could accomplish that goal.

Warning:
All modifications are done at your own risk! I am not responsible for any damage caused by the mods!

Source: http://www.techpowerup.com/articles/overclocking/voltmods/113/1