DFI NF4 Ultra-D vdimm mod: come inside.

[Tony]

So i have had a few mails asking about the mods I did. i know Malves has already posted but these still may help someone for the Vdimm. i have added the VTT also with the connections explained.

VTT:


Vdimm:


VTT is worth it IMO, i was able to gain a few fsb at 2.65V 300fsb+ and it did seem more stable, the pot swings the voltage either way.

[timpanogos]

any suggestions on how to tweak these two and there interactions? For example, I assume set the vdimm mod first, and then tweak the vtt mod to be 1/2 of vdimm?

Is that the idea?


any measuring points on the vtt mod better than others??
Thanks!!

[Tony]

any suggestions on how to tweak these two and there interactions? For example, I assume set the vdimm mod first, and then tweak the vtt mod to be 1/2 of vdimm?

Is that the idea?


Any measuring points on the vtt mod better than others??
Thanks!!

measure VTT on the 9173A, I just set Vdimm slowly and tweak VTT along with it. The dip is still there, but I was able to tweak VTT a little high, this reduced ther dip and gained stability.

next mod is to add another 9173 and see if the dip is reduced even further...all i have to do is find a source for the chip.

I was supprised to see how little Vdimm is actually really needed, 2.75V or so on a few dimms and usually 2.65 to 2.68V max's the dimms out.

[flexy]

hey bigtoe, thanks, very interested in the VTT mod. How much better is the VTT fluctuations with only this mod ? Or should we wait 'til we have some more info regarding a mod with maybe another 9173A ? I really want to totally eliminate those VTT fluctuations.

Regarding the mod: might it be possible that, instead of soldering to an R there is a pin right on the DIMM slot, some PIN where we can do that instead of the need to solder around on that resistor ? Just wondering

[EMC2]

--- Flexy --- Pin 1 & Pin 7 of the DIMM slots (Vref & Vdd respectively)... will go right down into the test point clips of the DIMM socket... this would allow you to raise Vtt only, no lowering (which you don't really want anyway). From my previous testing, doesn't change magnitude of the dips, only offsets them so absolute value isn't so low. Or use 1, 93, & 96 for up/down control (Vref, Gnd, VddQ respectively). Center leg of POT to pin 1 (Vref), outside leg(s) to other pin(s).

--- Tony --- Only place I've found any RT9173As was a distributor in NY stateside... and they had a minimum order of 100 :/ Just rob one off one of your other MBs

[timpanogos]

ouch on the min order!

[felinusz]

I have two questions for you folks

My 50K VRs (I ran out ) should be here tomorrow, I'm going to install VTT and VDIMM voltmods on my board when they do get here.


~ How hot can VTT be run,without compromising stability?

~ Is a hot VTT better than a low VTT for stability?

~ At what point does an above-reference VTT begin to adversely affect stability?

~ When you say "10K OHm VR set to midpoint", you mean 5K of resistance right?

Thanks, I'll be sure to share my results!

[craig588]

I just found something which brings all sorts of ridiculous ideas to mind, a 2 farad capacitor pack that came out of a dead power amp. It's like the size of a car battery, but if it has the potential to fix these VTT problems I would love to waste it on a motherboard. What points should I try attaching it to? (No rush, I'm out a videocard right now because of neweggs crappy refurb sales, at least they have a good RMA service)

[Tony]

I have two questions for you folks

My 50K VRs (I ran out ) should be here tomorrow, I'm going to install VTT and VDIMM voltmods on my board when they do get here.


~ How hot can VTT be run,without compromising stability?Depends on the dimms

~ Is a hot VTT better than a low VTT for stability?Slightly high is quite nice

~ At what point does an above-reference VTT begin to adversely affect stability?Again depends on dimms

~ When you say "10K OHm VR set to midpoint", you mean 5K of resistance right?Yes

Thanks, I'll be sure to share my results!

Check the quotes

[Tony]

Just rob one off one of your other MBs

Can't do that m8, all the boards I have here are different steppings, i need them for support.

I have been looking over the dead boards and none have the IC...looks like I will have to just find someone willing to sample them.

[felinusz]

Only place I've found any RT9173As was a distributor in NY stateside... and they had a minimum order of 100 :/ Just rob one off one of your other MBs

If someone can design a simple circuit for fixing the VTT flux, that could easily and simply be attached to the DFI nForce4 motherboard via pomona grabbers, I am sure we could easily find 100 people interested in a fix that cost ~$5-$10 to put together - practically every A64 user has this motherboard.

Of course, there is the issue of testing the circuit out first, which is impossible without one of these ICs in hand...

Check the quotes

Thank you Bigtoe, my board goes on the workbench right now (my 50K VRs just got here, mouser pulls through again ), I'll have some results from my board by tonight or tommorrow.

I just need to play some HL2 first (I always play a good hour or two of whatever game I'm enjoying before doing any voltmods - that way if I kill something I'll at least have had a good run of fun before doing so )...

[flexy]

If someone can design a simple circuit for fixing the VTT flux, that could easily and simply be attached to the DFI nForce4 motherboard via pomona grabbers, I am sure we could easily find 100 people interested in a fix that cost ~$5-$10 to put together - practically every A64 user has this motherboard.

yes....but then i really dont know whether 100 people would actually know what a VTT is nor ever heard of that there are issues with it.

Anyway i would buy/do that mod in a heartbeat...you could defintly count ME in...so we only need 99 more

[timpanogos]

... 98 ...

[stealth17]

→97

[EMC2]

--- Craig --- Don't do it Two problems... first is in-rush current, second is effective ESR and ESL. First one might fry your board, second one would make your mega-cap ineffective.

>>> teaser <<<

[Malves]

yes....but then i really dont know whether 100 people would actually know what a VTT is nor ever heard of that there are issues with it.

You're kidding, right?

[felinusz]

Malves, Bigtoe; your mods are done and work perfectly - thanks a lot guys!


The VDIMM mod did not get me any more or less stability when at the same overvoltage - before the mod my BH-5 ran at 278 MHz with complete memtest86 stability at 3.78V, after the mod it still peaks at the same frequency with that overvolt.

However, the mod looks to have netted me another 1 MHz (so far, I have only done very brief testing!) on my stable overclock, due to the VDIMM overvoltage fine-tuning that it allows. My board overvolts VDIMM a great deal, the overvolt increasing as BIOS VDIMM increased. At 3.7V in the BIOS, the board gave me 3.78V. At 3.8V in the BIOS, the board gave me 3.9V - all the overvoltage values in between this 0.12V gap were unnattainable. Now at 3.83V, my memory is running at 279 MHz with stability (for the ~10 minutes I have run it through memtest T5 anyhow), and I expect the peak bencheable speed shall have increased by ~1 Mhz as well. I have been running my BH-5 at 3.78V day-to-day... I expect this mod will be very useful.



The VTT mod works perfectly, and I took the liberty of making some multimeter measurements. In memtest86+ test#5, VTT is stable as a rock, as is VDIMM. In memtest86+ test #8, I see the same thing all of you are seeing - my VTT fluctuates between 1.91V and 1.94V (with VDIMM set to 3.83V). The VTT mod is a decent fix, I tweaked VTT to run a little hotter, so that it does not droop below reference - and the hot VTT does not adversely affect stability (although from my extremely brief testing thus far, it does not appear to be beneficial to stability either).

I'm going to spend some more time with the improved voltage control tommorrow, and see if more VTT fine-tuning will take this memory any farther.

→97

96.

[alpha0ne]

95 , and I think flexy you underestimate how many ppl really do know about these things

[CaTalyst.X]

Hrmm..were working on a circuit for the VTT fix..it will have to be something that is purchased and then soldered on or clipped on with leads, its not just a matter of soldering a VR in place :P

-CaT

[persivore]

Does anyone think my attatched circuit would work? R4 is used to decrease Vtt that the RT9173A gives out, so that only the new regulator controls Vtt, and R2/R3 are feedback resistors to provide gain to compensate for R4 to bring Vtt back to 1/2 Vdimm.

Does anyone know the value of the voltage divider resistors for the Vtt suppy so that I can put in some values for the resistors?

I'm using a similar circuit to this on my NF7-s to privide a Vtt supply that follows Vdimm (it doesn't have R3 or R4 and R2 is just a link to make it into a unity gain buffer). The IRF630 is rated to 6A iirc, so should be able to handle the Vtt supply.

[felinusz]

Hrmm..were working on a circuit for the VTT fix..it will have to be something that is purchased and then soldered on or clipped on with leads, its not just a matter of soldering a VR in place :P

Well, yeah, the VTT mod that bigtoe posted isn't a fix for the fluctuation, merely a means of running VTT slightly hot in order to minimize the negative effects of VTT dropping below reference 8-/.

VTT is still all over the place under certain conditions, and it's bad enough that it's even visible with a cheap multimeter.

[uwackme]

I sent Richtek a request for samples, will see what happens.

Simplest solution would be piggybacking a second 9137A. Use a piece of copper on TAB to raise height, use some AS Ceramique on body, and bend @2's pins down to solder onto #1's.

[Tony]

Hrmm..were working on a circuit for the VTT fix..it will have to be something that is purchased and then soldered on or clipped on with leads, its not just a matter of soldering a VR in place :P

-CaT

Its not a fix, but it does help, i have a feeling by the time we will see a true fix there will be a new board out without this issue ;-)

[dippyskoodlez]

Its not a fix, but it does help, i have a feeling by the time we will see a true fix there will be a new board out without this issue ;-)

*the* new board... the one with the ati gruper PWM by chance? lol

[stealth17]

Its not a fix, but it does help, i have a feeling by the time we will see a true fix there will be a new board out without this issue ;-)

just because there is a new board out doesnt mean everyone will upgrade. so the vtt fix will help people for a long time. even those that havent upgraded from socket A yet becuase of their low budget...