NF7 rev2 VTT mod need it so bad...

So the feedback resistor is R750. It is located between DIMM1 and DIMM2 near the winbond chip end. It appears to be a 120ohm resistor, but my eyes even with the magnifier arent that good. It measures 120. The pad on R750 nearest the DIMM levers is Vtt, the end nearer the middle of the DIMM is attached to the winbond chip pin2. So this is the feedback path. There is a missing R751 that goes between Pin2 (feedback) and GND, but that would be the opposite of what we want.

Ultimate change would be to replace R750 with a pot, but that would be VERY hard based on location. Our mod so far...adding resistence into the feedback path....cut trace, reconnect through small resistence. Even my EC3001 soldering iron cant get in there without harming the DIMM sockets.

So at least we have a place on the top of the board to measure other than the DIMM. R750 end near levers.

Quote:

---

Originally posted by Malves

Start trimmer at max? No. According to the IC specs there's no feedback divider. So, we have to "create" one, to trick the controller in feeding more VBT (Vbt=Vtt). You start at 0 omhs and raise the resistance to get more volts out of the controller.:) [/B]

---

Yes u are right Malve. This is wrong when u do the mod with inline sense trimmer, but not if u do it with one point on the Vbt sense and the other to the ground. (like the moboFAQ Vdimm way for example) Of course I prefer ur way, I just thought be more practical and safer to first just lower the V of the trace with grounding to see how reacts. :)
Congratulations guys I think U find it @last :D
Edit: To see if the cutting trace gives the same volts with the Vbt mesaure the legs D1 of the FDS9630A on the side of dimm3.
I have mesaure it many times and pin 2 of the Winbond and the 2 legs of the FDS fet mach in all 4 selections of BIOS (2.9 gives 3.08Vdimm that gives 1.54Vbt @least in my mobo)

Just did the vdimm mod and it works great. :)
I recommend this mod to others too!

And I follow the progress of the vtt-mod with excitement. Really hope it helps!

gentelman, we got ourselves a WINNER !!!!!!!!!!!!!!!!!!

1.6 vtt :toast:

pics to follow. !!!!!!!!!

:banana: :banana: :banana: :banana: :banana: :banana:
This is great news!!!!!!!!
bachus_anonym u take all the glory :D :slobber:
:toast:

Easy place to measure Vtt... there are a pair of 56ohm resistors for each channel. Channel A (DIMM1-2) is in area between DIMM2 and DIMM3 between a couple resistor packs (the multipin black resistor banks all over the place). Channel B's is on outside of DIMM3 about 1" from lever.

So Vtt at DIMM socket pin is result of Vtt passing through a 56ohm resistor.

i'm so excited !!!! guys, u r geniuses !!!

http://www.xtremesystems.org/forums/...id=33549&stc=1


http://www.xtremesystems.org/forums/...id=33550&stc=1


http://www.xtremesystems.org/forums/...id=33551&stc=1

if only it will go so smooth on my good board :-)

i need to calm down coz my hand are shaky now :-)

:toast: :toast:


Guys, take on it and post results...

good luck

:bounces: Gonna do that tomorrow:bounces:

DFI Infinity, here we come !!! Hopefully :D

:D very nice, good job :)

who figured this mod out? i amv ery curious who finally figured this board out.

we need to give credit where it is due... :)

How much is default Vdimm, 2.6V? (started mobo without CPU, Memorys and VGA)
I just measured my VBT and it showed 1.45V...not VBT modded

default is 2.6v... but on my test-mobo even when i clear CMOS and power it up it still shows 2.96vdimm and 1.6vtt... i guess i would need to get to BIOS and "save and exit" with default settings to get right readings at 2.6v...
which i can't do coz it's "dead" :D

Hmm, I measured before I cleared CMOS VBT=1.45V VDIMM=3.45V, after I cleared CMOS it was still VBT=1.45V VDIMM=3.45...
I have write down that 2.6V should be 3.14V, weird...

ok, it's time to take on my precious good board :-) hopefully it will be as easy as test one...

Mine at default 2.6V has Vtt of 1.37V, at 2.9V it's 1.54V... pre mod.

Do VDimm mod, VDimm sails off and Vtt stays 1.54V :rolleyes:

Interesting thing, before I do the mod, I using Kingston PC2100 value ram as ginuea pig. At stock 2.8V setting 200Mhz 11,3,3,2.5 CPUINT enb. If I turn up the VMod so Vdimm is 3.2V... errors it's ASS off at any speed. I have a feeling Vtt mod will wake this stuff up HARDCORE. It's very sensitive to the Vdimm Vtt disparity.

Ultimately, we'll just come up with a fixed resistor value that sets Vtt correctly for a higher Vdimm range, most people with CH5/BH5/BH6 chips wont need to bother with a pot. Just cut etch, and bridge with a small resistence...BUT... you will be tied to keeping VDimm in higher range, otherwise with Vdimm low you end up with the exact OPPOSITE situation, with Vtt too high vs Vdimm and unhappy rams.

The key here is that the DDR data bus is a transmission line, and the terminating resistors.."PULL MIDDLE" the lines. IE: they pull each signal to a point 1/2 way between a "0" and a "1" which for Vdimm 3.0V would be 1.5V. If Vtt is offset, then it is easier to make a "0" on the bus than it is to make a "1"... conversely it is HARDER to make a "1" and here at high speeds is where the ERROR comes from.

Once Vtt is dead center, you truly will find the REAL maximum speed your rams will operate at....at any given Vdimm. If Vtt is offset, you wont see the true maximum because "0"'s are easier to make than "1"'s....I hope that helps people understand WHY we need this.

Quote:

---

Originally posted by Dani
Hmm, I measured before I cleared CMOS VBT=1.45V VDIMM=3.45V, after I cleared CMOS it was still VBT=1.45V VDIMM=3.45...
I have write down that 2.6V should be 3.14V, weird...

---

When U clear CMOS the fail safe settings always sets the Vdimm at 2.8 in BIOS. The default Vdimm in this value should be around 2.9v (if I remember correctly) and the Vbt is 1.45v. If u done only the Vdimm mod the Vbt isn't effected and repents only from BIOS selection. So ur Vbt readings is correct, and ur Vdimm is wrong if u haven't done the mod (prompably u are measuring the 3.3 rail upon the fet.)

Ok, Im not sure what I measured but my +3.3 is around +3.85V:D
I have "normal" Vdimm mod...

Ok I got it then :D
U need definitely 1.7v Vbt if u are indeed around 3.4 Vdimm :D

The mod works correctly.

My Valueram doesn't like Vdimm over 2.9ish, but now Vtt is correct.

3.2Vdimm and 1.6Vtt

Ill go test the CH-5 ram now.

Good going guys ;)

WTG Fellas!!

I knew the guys at Xtreme would somehow get together on this and figure it out, dead boards help too it seems (B.A...;) )

Excellent, and some spare 2100 for guinea pig, heheheh

Great job guys, need data....... need data..........heheh
:thumbsup: :rocker:

OT: Marlborough and Andover huh?
Hmmmmm I live in Easton, I was in BOTH Marlborough and Andover TODAY!!

Go Sox!!!

very interesting :toast:

so the dfi nf2 just stop increasing vtt after 1.45v as well?

good question saaya.

I THOUGHT I saw a post where someone else said the VTT on the DFI board tracked correctly(up to 1.65/3.3v or something?).
I wasn't aware it was an issue with them.

So did I, but that could have been VBT.

Since VBT and VTT are supposed to be the same, shouldnt there be a way to link the sensors maybe?

hey guys,

so i finished modding my good board... :D

everything went just fine and after setting trimmer to 0 ohm vtt is now 1.52v (up from 1.49v) - vdimm in BIOS was 2.9v. what sucks though, is that i had to take mobo outside my case coz i used screwhole next to vdimm mod area to push wires thru. and now pc wouldn't even start with mobo inside the case... i need to figure out the way to put it back in :)

so, i don't know if i am at the point where ram limits me or what, but with 3.3 rai @ 3.8v, vdimm @ 3.5v and vtt @ 1.75 goldmemory generates no errors within 30mins only at 242FSB...

i need some more testing... i guess...

EDIT:There's very weird side effect of this mod... at 233FSB (3.35vdimm & 1.52vtt) goldmemory shows errors very quickly... but as soon as i make vtt exactly 1/2 vdimm - golmemory has no problem running for 30mins). so it looks like after the mod vtt always has to be 1/2 vdimm.... really weird...
and also, i haven't actually checked that before, but that little Dual-Mosfet that i take vtt measurements at gets REALLY HOT... i need to figure out how to cool it down... so far i have a fan blowing on it & memory slots...

better cool it down b4 it fry .... :D

Hey tictac...you got PM, bro. :)

Quote:

---

Originally posted by daos
who figured this mod out? i amv ery curious who finally figured this board out.

we need to give credit where it is due... :)

---

Credit Goes to:
enduracell : main idea
me... :D : just give some opinion and double check Malves Vtt trace
bachus_anonym: post pic of dead board with winbond ic remove
Malves: find the vtt trace and vtt mod from the pic
bachus anonym : beta test

Thanx for your time and aford we work as a team here... :toast:

i like that... i hope it clarifies all doubts :toast:

Looks like it does. :)

Hey bachus you got PM at the other forum.

EDIT:

EDIT2: Just checked VTT on my DFI. It looks like VTT tracks even with modded vdimm. I set it up to 3.5v and VTT went to 1.777. Unless I got VTT at the wrong spot, which I don't think so.

Quote:

---

Originally posted by uwackme
So the feedback resistor is R750. It is located between DIMM1 and DIMM2 near the winbond chip end. It appears to be a 120ohm resistor, but my eyes even with the magnifier arent that good. It measures 120. The pad on R750 nearest the DIMM levers is Vtt, the end nearer the middle of the DIMM is attached to the winbond chip pin2. So this is the feedback path. There is a missing R751 that goes between Pin2 (feedback) and GND, but that would be the opposite of what we want.

Ultimate change would be to replace R750 with a pot, but that would be VERY hard based on location. Our mod so far...adding resistence into the feedback path....cut trace, reconnect through small resistence. Even my EC3001 soldering iron cant get in there without harming the DIMM sockets.

So at least we have a place on the top of the board to measure other than the DIMM. R750 end near levers.

---

damn... i just snap out my vdimm slot no 1 just to re check what uwackme said...

ya....u r right the R750 is the terminal resistance of this vtt sense.... :thumbsup:

u dont need to snap the r750 off... we can solder a wire with a trimmer to R750 leg (near the missing r751.. away from the near lever) and ground it (same method as Motherboardfaqs vdimm mod theory)....
the theory is to increase the resistance

Another way of Vtt mod (Incase u dont want to cut any trace on ur PCB)

any other idea coming?
If we can find vtt pin on dimm solder point( we can solder vdd voltage to that pin ... same as Dirty_Punk vdimm mod did)

any 1 can find where is the vtt pin below the dimm?

Here the 2nd method(Alternative method of Vbt/Vtt mod)
Thanx to Uwackme.... :thumbsup: u make me snap off my dimm slot 1... hehehe

anyway its dead already no big deal... :D

Wait, I dont get anything for saying it would work? ;)

ic dfi have higher vtt voltage.... hehehe :D

edited: i just measure my R750 resistance its about 107 Ohm :toast:

can some1 measure the voltage on the pin i mark here.

If it is the right pin.... we can try solder Vagp/vdd to the vtt pin

same ways as dirty punk vdimm mod did

Quote:

---

Originally posted by Malves
EDIT: Just to add. It's a good idea to ground the trimmer somewhere. Using the 3rd leg of it. It helps stabilize voltage.

---

i hope this helps coz that's other thing i noticed.... at same 3.3v rail and same vdimm - vdimm fluctuates a bit... that wasn't the case before the mod. i guess i need to ground this trimmer now...

thanx

OK, been testing for hours.

Mod works fine, set 3.3Vdimm Vtt tracked 1.65V. My CH-5 1Gig of it ran 230Mhz 11,3,3,2.5 cpuint enb dual channel. Previous high was 220Mhz. This was on D23-3Dfire. Main system has D10, Ill have to pull it apart now. I think my 350W PS has overvoltage on 3.3 rail that Im just nibbling setting it to 3.6V, the main systems 530W supply has more headroom.

The Vdimm regulator NEEDS some margin to operate correctly. With RAIL at 3.3V and Vdimm at 3.3V yes you will see ALOT of instability because the Vdimm regulator (a little single voltage switching powersupply) is flipping out. You need to keep RAIL .2-.3V above Vdimm. You will see, as you gradually increase Vdimm turning the pot that suddenly the voltage goes from solid rock stable to wildly fluctuating. That is NOT good for stability and Happy-Ram. So set rail to 3.6V by modding your PSU...my Fortrons 350 and 530 PSU's both have rail adjustment pots.

On the Vtt mosfet... it's just like the one's under the "PLATE" on ATI 9700pro cards, and now especially could use some cooling, Im slapping a baby microcool sink on mine. Amazingly, the Vdimm mosfet stays pretty darn cool.

Im looking up the DDR DIMM spec now, need to verify that VREF is set correctly... that it tracks Vdimm. And what is value of VDD and VDDQ in the DDR spec. Spec I guess says the Vdimm mod changes "VDD" and "VDDQ" is fixed at 2.5V...hmmm

So pin 1 of the DIMM's is on the CPU side of the opposite end from the Vdimm regulator. Pin 1 is Vref, Pin 7 is VDD, pin 15 is VDDQ.

On the Valueram, VDDQ and VDD are equal, the in the JEDEC spec for DDR DIMMs a pin on the stick determines if VDDQ tracks VDD or not. I didnt look on the CH-5's but Winbond spec has VDD/VDDQ at 2.5V each default.

Pin 1 is Vref.... it tracks Vtt as it should, spec'd at Vtt +/- .04V. Must wonder if the Vref MAXIMUM spec is a risk with this Vtt mod. Since VDDQ max is 3.6V....Vtt(Vref) max is 1.8V....dont go over it.

Vref is spec'd at DAMN well better be 1/2VDDQ :rolleyes:
So all this time, with Vtt not following Vdimm correctly, we were out of spec with DDR design parameters.

grounding trimmer's third leg, like malves advised, to the screwhole prevents system from starting - i mean it starts but screen stays black...

are you starting at the high or low setting of the trimmer, and what size trimmer are you using? May need 1-50k.

can anyone build a completely new vbt divider circuit .... so that vbt will always stay 1/2 of vdimm voltage like MadCat1968 IC7-Max3 Vbt divider circuit.... :D

On the trimmer value...we are only inserting a small additional resistence into the feedback path for Vbt. So 10-22-33ohm ish amount is all you end up setting the POT to. The R750 we are "enhancing" here is only 120ohm resistor. We are adding a little bit more in series with this 120ohm. It doesnt take much to raise Vtt from 1.45V (2.9V bios setting) to 1.6-1.7V for Vdimm modified to 3.3-3.4V. Just do all this with Bios setting at 2.9V, and you can lower the setting and Vtt paces Vdimm correctly. All we have done really is move UP to a higher range....from 2.6-2.9(1.3-1.45) stock settings to a new range of 2.9-3.3(1.45-1.65) for example.

This additional resistence INCREASES the voltage on the FB pin...trying to tie it to ground through a resistor would DECREASE the FB pin value and LOWER Vtt. So a high value pot tied to Vdimm might actually work instead....bleeding voltage into the FB pin, the analog of increasing R750. This might actually result in Vtt tracking Vdimm rather than you needing to track it manually with BOTH pots. A "set and forget" 2nd pot. Someone should give it a whirl. A 50K pot for starters...set to max and slowly turned down while watching Vtt at a set Vdimm.

Ultimate fix for all this is a completely different Vdimm mod.

We need to find the point where the BIOS setting controls BOTH Vdimm and Vtt in parallel. Stock the board does have Vdimm/Vtt correct and insync and they track. The current Vdimm mod...normal or DirtyPunk...is done at point in the circuit AFTER the Vtt control is made. So Vtt no longer tracks Vdimm.

Since it is 2.6...2.7...2.8...2.9 I'd venture a guess it is a 2 bit register setting in the Northbridge. Now does it leave as 2 digital bits that power a voltage divider network to drive the regulator's control input. Or does the northbridge output an analog vltage used as reference for the regulators. IE: 0,0 = 2.6V; 0,1 = 2.7V; 1,0 = 2.8V; 1,1 = 2.9V. And we modify it to be: 0,0 = lowest new V....... 1,1 = highest new V. All the while Vtt tracking correctly.

If we can find the point where both are together...output of northbridge to the regulators...and alter THIS with a mod, then both will simply track, but start at a mutual (and correct) higher default setting.

It's really now just a matter of finding that point. Requires completely reverse engineeing the Vdimm/Vtt regulator design. Not too hard, I'd be a lot easier if I had a DEAD board to use as a road map....and pull parts off as needed. The basic prototype is sitting in the Winbond/etc data sheets for the chips involved.

In the meantime, guess today is RiptheSystemApart...AGAIN day :slobber:

:eek:
Did the mod today but didnt solder wires yet:cool:

http://muljas2.mine.nu/dani/Tietokon...0VBT%20mod.JPG

Quote:

---

Originally posted by uwackme
On the trimmer value...we are only inserting a small additional resistence into the feedback path for Vbt. So 10-22-33ohm ish amount is all you end up setting the POT to. The R750 we are "enhancing" here is only 120ohm resistor. We are adding a little bit more in series with this 120ohm. It doesnt take much to raise Vtt from 1.45V (2.9V bios setting) to 1.6-1.7V for Vdimm modified to 3.3-3.4V. Just do all this with Bios setting at 2.9V, and you can lower the setting and Vtt paces Vdimm correctly. All we have done really is move UP to a higher range....from 2.6-2.9(1.3-1.45) stock settings to a new range of 2.9-3.3(1.45-1.65) for example.

This additional resistence INCREASES the voltage on the FB pin...trying to tie it to ground through a resistor would DECREASE the FB pin value and LOWER Vtt. So a high value pot tied to Vdimm might actually work instead....bleeding voltage into the FB pin, the analog of increasing R750. This might actually result in Vtt tracking Vdimm rather than you needing to track it manually with BOTH pots. A "set and forget" 2nd pot. Someone should give it a whirl. A 50K pot for starters...set to max and slowly turned down while watching Vtt at a set Vdimm.

Ultimate fix for all this is a completely different Vdimm mod.

We need to find the point where the BIOS setting controls BOTH Vdimm and Vtt in parallel. Stock the board does have Vdimm/Vtt correct and insync and they track. The current Vdimm mod...normal or DirtyPunk...is done at point in the circuit AFTER the Vtt control is made. So Vtt no longer tracks Vdimm.

Since it is 2.6...2.7...2.8...2.9 I'd venture a guess it is a 2 bit register setting in the Northbridge. Now does it leave as 2 digital bits that power a voltage divider network to drive the regulator's control input. Or does the northbridge output an analog vltage used as reference for the regulators. IE: 0,0 = 2.6V; 0,1 = 2.7V; 1,0 = 2.8V; 1,1 = 2.9V. And we modify it to be: 0,0 = lowest new V....... 1,1 = highest new V. All the while Vtt tracking correctly.

If we can find the point where both are together...output of northbridge to the regulators...and alter THIS with a mod, then both will simply track, but start at a mutual (and correct) higher default setting.

It's really now just a matter of finding that point. Requires completely reverse engineeing the Vdimm/Vtt regulator design. Not too hard, I'd be a lot easier if I had a DEAD board to use as a road map....and pull parts off as needed. The basic prototype is sitting in the Winbond/etc data sheets for the chips involved.

In the meantime, guess today is RiptheSystemApart...AGAIN day :slobber:

---

Cheers to a man that certainly knows his stuff.

Thanks for all your help man.

i'm gonna look this thread over again tomorrow, when i'm not tired, and see what exactly we're doing with this mod.

way to go Stang_Man..... :D GL :thumbsup:

Bachus_anonym

I just check my dead board and compare it ... there are missing mosfet in ur board...

i'm confused here... do u remove it .... what mod is that for?

here my dead board(NF7-S Rev2.0) mosfet near the sata connector :confused:

Vbt=Vdd mod.... delete

result:
2 dead board (Mistamasta from AMDMB.com & asus from lowyat.net)
1 Safe (Mickey Padge Xtremesystem.org)

I certainly like not having to cut traces, but what if you want to run a high Vdd??

You certainly cant run a 2v Vdd under these circumstances, or even 1.85v+......unless of course you are running a Vdimm of 3.7v.

Granted, most people are not going to be running a Vdimm of more than 3.4v for daily use....or even lower...but not being able to run a Vdd above 1.8v is quite a loss.

Myself, I am not entirely sure that such a high Vdd is needed...but I like to be able to go to 2v if I want.

Anyone have input on whether a Vdd of more than 1.7v is a necessity or not?

Regardless, thats one hell of a nice find tictac!! :toast:

i tested the mod already on my dead board

some how it manage to power on once again... here i measure with my DDM....

12V @ 13.5V
3.3v @ 3.9V
Vdd @ 1.63V
Vbt @ 1.63v
Vdimm @ 3.9v ( I had done vdimm = i/o mod)

well if u have very high vdd voltage(1.8 or > 2.0V )... there is still way to do it... cut the wire and put trimmer on the white line.....

start from o ohm... raise the resistance to lower the Vbt voltage... :D

Quote:

---

Originally posted by tictac
i tested the mod already on my dead board

some how it manage to power on once again... here i measure with my DDM....

12V @ 13.5V
3.3v @ 3.9V
Vdd @ 1.63V
Vbt @ 1.63v
Vdimm @ 3.9v ( I had done vdimm = i/o mod)

---

3.9V on your mem? Nice ...
Is this measured on the vdimm mosfet or is it the bios value?

DDM ... digital multimeter...

on mosfet

sorry but connecting the +3.3v line to the VDDR power directly power up my VTT to an half of the +3.3v voltage, so with this mod no VTT mod is required, or i'm wrong.... i have measured VTT under the dimm slot, not on the mosfet...

Dirty_Punk.... is it VDIMM mod to 3.3V power conector, power up VTT to an half of the +3.3v voltage ?
I do it to,.. but it isn't half of the +3.3v voltage... or maybe I measured it wrong ?

what about, if I use V I/O, add some fix resistor to reduce it, and add trimer (pot) to make it half of VDimm, than take it to VBT pin..?

Quote:

---

Originally posted by Dirty_Punk
sorry but connecting the +3.3v line to the VDDR power directly power up my VTT to an half of the +3.3v voltage, so with this mod no VTT mod is required, or i'm wrong.... i have measured VTT under the dimm slot, not on the mosfet...

---

try measure on the mosfet or the R750 leg facing the near lever... the vtt is not half of vdimm voltage after vdimm mod... :(

u can also measure vtt on ce 48 & ce53 Rubycon caps.... :)

Also, you can measure Vtt at the DIMM itself... use empty socket..pin 1 is Vref...aka..Vtt. Pin 1 end of Socket is at edge of PCboard end of DIMM. Pin 1 side is the side closest to the CPU socket. So pin 1 of DIMM1 is the pin closest to the Winbond volt/fan monitoring chip between DIMMs and CPU socket. Pin 7 is VDimm on same DIMM socket. Sharp multimeter probes are a plus here ;-)

That VDD "boost" mod in your picture TicTac shorts the 5Volt rail to something in the VDD circuit.... I would NOT recommend it.

I would also not recomend the other shortcut method... shorting 3.3V rail to Vdimm, or shorting VDD to Vtt... since those are driven by switching regulator circuits that are going to be in an unknown state.... the outputs driven higher than inputs. Could lead to damage longterm, and even component failure and unknown consequences.

Provided the 3.3V rail is held .3-.4V higher than the intended Vdimm voltage, the Vdimm regulator circuit works just fine and with complete stability. The current capacity is WELL beyond what the DDR's need...hence the Vdimm mosfet never really gets hot.

If you have voltage instability....wild fluctuations....in you Vdimm when set higher by the mod, it means your 3.3V rail is simply NOT high enuff. Go into your PSU and raise it, or use the 3.3Vsense PSU mod.

Also an issue, in raising 3.3V rail with PSU mods, most PSU's have overvoltage protection levels, and it's possible to reach high enough to start triggering this....leading to weird fluctuations in 3.3V rail. Im fortunate in that the Fortron530 has 3.3-5-12V adjustment pots AND pots on the overvoltage levels. Some dont have this and you may not be able to get your 3.3V rail to 3.6-3.7 with stability, especially at high operating temperatures after hours of gaming. You will NEED a serious power supply when pushing the NF7 this hard.... 530W Fortron or 550W SuperFlower are my recomendations (both $70-80 at Newegg, Directron, etc)

It's a tough balance, having VDD adjustable is nice, though I havent tested extensively on the impact it has on overclocking.... but I have the Swifty on the NB to handle up to 2.0Vdd. Question is, does the Vdd level impact the Northbridge's end of the memory transfer levels. If you goose Vdimm (and therefore VDDQ) then the rams are working at a voltage level above normal.

The DDR signals all go to the NB chip, so does it also need to be goosed..or does the NB have seperate power pins ALSO powered by Vdimm (vddq) to set the reference level at which the DDR transceivers within operate? Without the NB spec sheet, this is unknown.

When I pull this sytem apart...with mods on everything, ill test extensively the impact of Vdd mod vs Vdimm/ram speed.

just to add up another thing:

The Dirty Punk vdimm mod is as same as normal vdimm mod... except
- the normal vdimm mod get their voltage from mosfet
- the dirty punk vdimm mod get their main voltage from i/o volt...

And there is no others circuit after the Vdimm mosfet to the dimm slot...

Measure the resistance between Dirty_Punk dimm solder point to the Vdimm Mosfet Leg.... The resistance is ZER0

Let me explain....

By shorting the Vdimm line to the 3.3V rail, you place the output mosfet of the Vdimm circuit in a battle with the output mosfet of the 3.3Vrail in your PSU. The Vdimm circuit mosfet now has it;s output driven to a higher/equal voltage than it's input...and they dont like that. It may never be an issue, but it may also end in damage to the transistor.... there really is no reason to bother sans for saving the $3 for a POT to properly mod the Vdimm.

Yes it is very stable, but so is Vdimm mod with a pot provided you raise your 3.3V rail to make room for the raising of Vdimm. You need to provide "some" headroom. Provided this is done, you'll see rock solid stable Vdimm from normal mod. if you see fluctuations it is because the 3.3V rail is too low for the regulator to work properly.

I simply recommend you stick with the POT method, no point in risking damage needlessly. Im not even worried about the motherboard, $60 refurb on Newegg is cheap... but $400 in BH5 ram, I dont think anyone should be risking with the simpler direct to 3.3V mod. We also dont know how the Vdimm(vddq) issue ties into the Northbridge chip, and what affect shorting to 3.3V rail might have longterm on that chip. Modder beware is all Im saying.

Quote:

---

Originally posted by tictac
Bachus_anonym

I just check my dead board and compare it ... there are missing mosfet in ur board...

i'm confused here... do u remove it .... what mod is that for?

here my dead board(NF7-S Rev2.0) mosfet near the sata connector :confused:

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WOW! u got me on that one... i have no clue! ATM, i have three board on hand... a good one (it has mosfet), "dead" one (no mosfet) and really dead also with mosfet...

i wonder what is that mosfet for ???

EDIT: tracing it leads to battery socket... hmm

About that mosfet I have it too

About increasing Vdd = more OC on FSB... can´t reach more FSB with high Vdd´s. 243 MHz @ 1,6V or 2V...

About Vtt mod...
Can´t it be done by the 3,3V line + pot and tune it to the desired voltage? Or this have the same effect of dirty_punk Vdimm mod?
I mean this effect... :D

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By shorting the Vdimm line to the 3.3V rail, you place the output mosfet of the Vdimm circuit in a battle with the output mosfet of the 3.3Vrail in your PSU.

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And thanks uwackme for the tips...

btw, I have solid Vdimm, from the typical Vdimm mod, and Vdimm mosfet doesn´t get really warm.

Keep the good work guys :)

Some NF7s don't like high vdd, some do. My first didn't, my second did.

Can someone post results before and after the mod? I'd like to know if this is really going to help.

Quote:

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Originally posted by HaLDoL
Can someone post results before and after the mod? I'd like to know if this is really going to help.

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http://www.xtremesystems.org/forums/...threadid=33240

Quote:

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Originally posted by uwackme
Also, you can measure Vtt at the DIMM itself... use empty socket..pin 1 is Vref...aka..Vtt. Pin 1 end of Socket is at edge of PCboard end of DIMM. Pin 1 side is the side closest to the CPU socket. So pin 1 of DIMM1 is the pin closest to the Winbond volt/fan monitoring chip between DIMMs and CPU socket. Pin 7 is VDimm on same DIMM socket. Sharp multimeter probes are a plus here ;-)

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i have measured on the DIMM socket the VTT, not on the mosfet... so on the dimm socket i measured over 1.7v with over 3.4v of VDDR, but this with power off motherboard (also VDDR can be measured with power off motherboard with this mod, with normal mod not because you measure always aroud 2.85v)

howether with +3.3v directly connected to dimm pin you get a much more stable VDIMM
with both at 3.2v i get about 3-5mhz more with this mod VS normal VDDR mod

When the Vdimm regulator is working correctly...ie: 3.3V rail is high enough over Vdimm desired...I get +/- .01V stability on the 4 boards I've fiddle with this week. All 4 systems have Fortron supplies with 3.3V adjustment inside though.

On the before/after results.....D23 3Dfire bios, Fortron 350W supply, 3.3V rail @ 3.6V, normal Vdimm mod, cut/pot Vtt mod, NO Vdd mod on this board yet, so stock 1.7V setting.

PC2100 valueram: 3.0Vdimm 1.5Vtt

Before 2x 256M 200Mhz, 11,3,3,2.5 cpuint enb, total stability

After 2x 256M 210Mhz 11,3,3,2.5 cpuint enb, total stability.

HyperX PC3500 CH-5 chips: 3.3Vdimm 1.65Vtt

Before: 1Gig 220Mhz 11,3,3,2.5 cpuint enb, total stability

After: 1Gig 230Mhz 11,3,3,2.5 cpuint enb, total stability.

So it's definitely worth doing in my book. not the panacea I was hoping for with CH-5 chips, but still better.

Ill have D10 bios results on a fully mod'd board with 530W supply later today. This board already does 220Mhz 11,3,2,cas2 cpuint enb with 1Gig....3.4Vdimm, 1.85Vdd, and no Vtt mod.

Total stability meaning memtest83 v3.0 and M$oft memory test running errors free for 20 passes on extended tests.

Quote:

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Originally posted by uwackme
Let me explain....

By shorting the Vdimm line to the 3.3V rail, you place the output mosfet of the Vdimm circuit in a battle with the output mosfet of the 3.3Vrail in your PSU. The Vdimm circuit mosfet now has it;s output driven to a higher/equal voltage than it's input...and they dont like that. It may never be an issue, but it may also end in damage to the transistor.... there really is no reason to bother sans for saving the $3 for a POT to properly mod the Vdimm.

Yes it is very stable, but so is Vdimm mod with a pot provided you raise your 3.3V rail to make room for the raising of Vdimm. You need to provide "some" headroom. Provided this is done, you'll see rock solid stable Vdimm from normal mod. if you see fluctuations it is because the 3.3V rail is too low for the regulator to work properly.

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i have tryed both and with very different results..

with +3.3v at 3.5v and VDDR at 3.2v with normal VDDR mod i can get max to 250mhz only sandra benchable 2 stick of V-Data PC3200

with the +3.3v at 3.2v but directly connected to vdimm i have a rock stable vdimm (and this isn't so easy with NF7-S and dual channel) and can bench sandra at 255mhz (probably a bit over) and 250-252 s.pi with the same sticks of ram

i think that the power circuit of the VDDR on the NF7 when DC is enable has a great hit on stability... so bypassing it give much more stable VDDR...

howether i'm can't recommend this mod for 24/7h use because as you say we can't know exactly if the mosfet like or not this situation...

when u gona do Vbt mod Dirty_Punk?

it worth a try... :cool:

:toast:

My frens manage to Hit 260MHz FSB with your Vdimm mod
http://downloads.modlabs.net/bios/pic/asus.jpg

right, my try is without VTT mod... i must try with that, but now i haven't yet the V-Data memory so i must try with other ram...

if you set the VTT more than 1/2 or the VDDR, like 1.7v instead of 1.65v, can you have better results on overclock or not???

howether the biggest problem of the NF7 in overclock IMHO is the chipset... isn't strange that DFI with more VDD get more mhz and NF7 with only 1.5v get the max and more VDD doesn't give anything???

and another thing.... if i'm right MSI has done a new nforce mobo with great voltage options in bios, like 2.3v vcore, 3.3v vmem ecc ecc... and it have a voice that seems to be a "secondary VDD voltage" that can be overvolted (i'm not sure), can be this the problem of the NF7?!? that NF7 doen't overvolt this "secondary VDD voltage" together with normal VDD and DFI do this????
it's only an idea and doesn't know if it can right or only a stupid idea :D

ya the is other mosfet beside the vdd mosfet . What mosfet is that? is that the secondry vdd voltage....

which MSI board is that?

emmm... my fren with a screen shot 260MHz 2-2-2-11 timing

now his board is dead after trying to do the Vbt mod....

Vbt=Vdd mod

:( :( :(

anyone have same issue here?

hoether only fot the overclock test the easyest mod is connecting +3.3v to vdimm, no difficult soldering, no warranty void..

better dont do my vdd=vbt mod

i will remove it then.... :(

another dead story here:(mistamasta)
http://forums.amdmb.com/showthread.p...5&pagenumber=4

Im doing tests now....

Weird results, at full Gig results on main board worse than before mod.

11,3,3,2.5 still error even at 220Mhz.

BUT...WTF...the 2x 256M sticks, 11,2,2,cas2 cpuint enb at...

drumroll... 245Mhzx10!!!!!! 3.3Vdimm 1.65Vtt... I assume this must mean BH5 or BH6 worst case.

The Vdd right now is 1.65 also, and going higher dont help, and lower will error. Going up to 1.95Vdd doesnt hurt either.

My poor 512M stick will need review.

The ODD thing is on the other NF7-S the full 1Gig was happy at 230Mhz 11,3,3,2.5 so there must be a diff between both these rev2.0 NF7-S's.

Ill keep you posted.

Well, 67 passes through Memtest86, no errors.

Im typing on the 512M stick at 230Mhzx10 11,3,3,2.5 cpuenb 3.3Vdimm 1.65Vtt on the backup system, also without error.

Ill move this alone into main system, and see where it goes.

Wonder if CH5 and BH5 cant get along well in same system.

Swap things, the 512M stick is in the main system, 3.3Vdimm, 1.65Vtt, 1.80Vdd, running 230Mhz 11,2,2,cas2.0 cpuint enb.

When all three sticks are installed however, instability/errors ensue.

That is all with bios D10.... now Ill begin testing D23 3Dfire.

Also, now typing on 2x 256M sticks in backup system, 230Mhz 11,2,2,cas2.0 3.3Vdimm, 1.65Vtt, 1.65Vdd.

Maybe mix+match BH5 and CH5 causes some weirdness?
Also, the 512M stick gets alot hotter in operation...16 chips instead of just 8 on a 256M stick.

Beginning to think these heatspredders are insulators instead :slobber:

The Vtt mod has seriously made improvement in how high an FSB good ram timings can go to.

have u try higher vdimm?

Vdimm @ 3.4v Vbt @ 1.7V?

Weirder and weirder dept.

On D23 testing of main board...the same 2x 256M sticks....same settings in all things.

230Mhzx10 11,2,2,cas2.0 cpuint enb went 100 passes error free.

235Mhz...errors on all timings. 11,2,2,2 11,3,2,2 11,3,2,2.5 11,3,3,2 11,3,3,2.5

240Mhz errors on all timings. This was dimm#1+3 or dimm#2+3

With the single 512M stick, all same settings.......

240Mhz would not even boot...no post...this is single channel, possible data point there. The 2x 256 would post and run @240Mhz.

235x10 11,3,3,2.5 and 11,3,2,2 worked flawlessly.

230Mhzx10 11,2,2,2 was flawless.

Ok, so something in D23 (and all newer BIOS's code) is different from D10, NVidia/Abit put some changes in that limited our topend regardless of circumstances.

Now for totally WACKO... back to D10, work on the 1Gig issue. Before the mod it was working fine at 220, after the mod...oh oh it was erroring. So I started testing each variable one at a time.

Vdd...1.6-1.95 no effect, still errors, return to 1.8Vdd that was used in all previous tests.

VDimm...3.0-3.35Vdimm....no affect or some worsening. Return to 3.3Vdimm

Vtt...hmm...return to lowest setting, like the bad condition from premod...BINGO! works again, no errors. With pot installed and set to min, new Vtt is still higher at Vtt= 1.545Vtt. This setting yeilds no errors...220Mhzx10 or 230Mhzx10 with 1Gig in place. Though at 230, the rams get hot in the 3 DIMM arrangement, out of the case, I need to rig a fan on them. The word OUCH comes to mind touching them. The world needs a better DDR heatspredder....mounted with ArticCeramique with FINS...instead of those stupid LEDs on the new Corsairs ;-)

TicTac...no for some reason none of these boards does 3.4V comfortably, regardless of 3.3V rail setting...tried 3.6-3.7-3.8 rail, but anything over 3.35V caused weirdness...pot was no longer effective, etc. I think a overvoltage element must be in the VDimm regulator circuit.

Going by the rams, 245x10 11,2,2,2 cpuint enb is plenty fast @3.3V....so I dont think I need 3.4V.

Now Im going to put the 9800pro in on the bench and see if it's presence alters the results at all. Then Ill be off to reassembly and Windowsland.

I guess I should peek under the 512M's heatspredder...is it ch-5 or not. 11,2,2,2 cpuint enb 3.3V @ 233Mhzx10 for a couple hours no errors....hmmm

So either 2x256 or 1x512 are both happiest with 1.65Vtt 3.3Vdimm but together...they want 3.3Vdimm and 1.545Vtt... weird....not 1.55Vtt...but 1.545Vtt :D

seem the board overheated too much after the vbt mod

my friends fry his vbt n channel mosfet... he didnt put heatsink on those mosfet....

do u think after we did the vbt mod it also effect other voltage than vbt.... ?

i have used VDDR up to 3.6-3.65v so VTT up to 1.8-1.825v and no problem with my mod yet.... howether it's very hight voltages and only for test use (max try 8h of stress) so in this case connect direct +3.3v is better and easyer

Quote:

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Originally posted by Dirty_Punk
i have measured on the DIMM socket the VTT, not on the mosfet... so on the dimm socket i measured over 1.7v with over 3.4v of VDDR, but this with power off motherboard (also VDDR can be measured with power off motherboard with this mod, with normal mod not because you measure always aroud 2.85v)

howether with +3.3v directly connected to dimm pin you get a much more stable VDIMM
with both at 3.2v i get about 3-5mhz more with this mod VS normal VDDR mod

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Pin 1 is Vref:
Pin 2 is Vtt :
Pin 7 is vdimm :
Pin 15 is Vdimm :

So do u mean Vref is the real Vtt voltage on the Rams

i'm getting lost here... :(

i have never measuered voltages on mosfet or else, always used the Dimm slot because only in the slot you get real voltages...

DDR pin map

if the pin 1 is the real vtt

i think u r probably right

coz i have measure the pin 1 it shown: 1.95-1.98v(half of my vdimm reading)

i/o volt = 3.95v
vdimm = 3.95v (Vdimm = V i/o mod)

and i also measure from the vbt mosfet it shown 1.63V(Vbt=Vdd mod)

vdd= 1.63v

Edited: Now what mod is this for? :(

probably Vbt mosfet doesn't get its voltage from VDDR mosfet and divide by 2 (and this explains why VTT isn't 0.5*VDDR when we have a standard VDDR mod) but gets it from another point

ok now there are 4 voltage to check:

V ref = half od Vdimm
V dd = Vdimm
V tt = half of Vdimm
V ih = half of vdimm

Vref is correct it shown half of vdimm voltage (after Vdimm=V I/O mod)

Have u measure the others volt.... Vtt and Vih?

Vref is not Vtt

Vtt is not Vref

as shown on the pdf file u give there :stick:

here... i just check my dead board voltage reading all over again

1st row is Vdimm mod Dirty Punk Ways(Take note that my winbond ic leg no 11-20 is gone)

2nd row Vdimm mod Dirty_Punk Ways + Vbt=Vdd mod

The Vref track the vdimm correctly after dirty punk vdimm mod
But i cant check my vtt as my winbond ic messed up

after i add vbt=vdd mod
the pin 2 of dimm show 1.7V same reading as my Vbt mosfet reading and Vdd reading
I measure pin 2 of winbond ic (Vbt sense line it show 1.6V)
Even after my vdimm @ 4V the vtt didnt track the half vdimm voltage correctly...

cheers :toast:

Well, there are 4 voltages on a DDR, Vdd-Vddq-Vref-Vtt

On the DDR dimms on most motherboards... Vdd and Vddq are simply run off the same source and are equal. So all Vdd and Vddq pins are soldered to the same PCBoard power plane.

On my NF7-S's the Vtt and Vref are very definitely connected together and are the same. And the Vtt mosfet gets hotter with Vdimm mod's due to the fact that it runs the terminating resistors, NOT because of the DDR chips themselves and Vref supply.

Think about it, the purpose of Vtt is to "pull-middle" the data lines so that the data bus sits IDLE in a Vtt state...is not allowed to drift to 0volts or 3.3Volts. Reason being, so that which ever direction the data pin needs to go...IDLE to a "1" or IDLE to a "0" the line only has to move from 1.65V to 0V or 1.65V to 3.3V.

The instantaneous current draw of the data bus going from 0V to 3.3V at DDR speeds would be astronomical. As it is, going from 0V-1.3V-2.6V leads to a certain amount of heat generation from the stock level of current draw through the mosfet. Increasing Vdimm you now go 0V-1.65V-3.3V increasing the difference from 1.3V to 1.65V which yeilds a current increase of ~18%... so the mosfet gets ALOT warmer than stock settings.

The mention on AMDMB about one GLOWING RED, comes from a fight between voltage regulator outputs.... where they both try and supply to Vxxx and if ONE regulator is particularly WEAK, the little mosfet has to not only supply Vtt/ref to the rams but ALSO attempt to DRAG the Vdd regulator's output UP in voltage, all the while the Vdd regulator is trying to "REGULATE" and keep Vdd lower, so they fight and one of them burns out.

Remember, 50% of the mod's you find on the boards are developed by PSEUDO engineering, not real engineering. So beware just slapping wires and interconnecting circuits. Things are usually design a certain way for good reason. Sometimes the reason is cost, and thats why wedont have a seperate Vtt control in the bios, etc; or why Vdd and Vddq of the DDR chips are both tied together in the design as Vdimm.

Remember, DDR is DDR... the same volt mod's and setup on the 9700/9800pro video cards holds true on the motherboards. But the video cards are going WAY WAY out of the way to get maximum performance. The motherboard designers figure, hell the rams are slow anyway, why bust our humps and add cost for negligible increases in speed/timing.

I'd personally LOVE to see someone slap 16 2.8ns Samsung videoDDR's onto some DIMMs and let us get REAL BUSY, FK 5ns BH5's :D :D

Tictac,.... it's me TrueEnd, I already make 3 in one mod for my board, and it's Rock Solid at FSB 240 at 2-2-2-11,...:toast: Great Job man,.. I use VBT mod,... and there's no problem yet,... it's the 3rd day since I use that mod,... I use VDD = VBT = 1.7V , VIO = VDIMM = 3.4V
I use the 3rd methode,.... I think it's no problem for my BH-6
:banana: :p:

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Originally posted by hyem
Tictac,.... it's me TrueEnd, I already make 3 in one mod for my board, and it's Rock Solid at FSB 240 at 2-2-2-11,...:toast: Great Job man,.. I use VBT mod,... and there's no problem yet,... it's the 3rd day since I use that mod,... I use VDD = VBT = 1.7V , VIO = VDIMM = 3.4V
I use the 3rd methode,.... I think it's no problem for my BH-6
:banana: kalo menang Special Price lah,.. :p:

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:slobber: wah.... nice :thumbsup:
:banana:

p/s : ntar kalau menang nf7s yg baru kasi special price dong.... kikiki :D :toast:

I dont recomend new user to try this new ways of Vtt/Vbt mod

but if u have done Vbt=Vdd mod .... and it is SAFE
here is better way to track back the vtt/vbt half of Vdimm voltage automatic without have to set vdd half of vdimm voltage anymore

The Vref track half of Vdimm voltage correctly even after Vdimm mod...
The only problem is the Vbt/Vtt Voltage didnt follow it ...

Vref = Always Half of Vdimm Voltage even after a vdimm mod

By this: 4th Method

Vbt/Vtt Voltage = Vref Voltage
( Always Half Of Vdimm Voltage & No need to adjust it anymore... )

For those who have tested my 3rd method Vdd=Vbt/Vtt mod SAFE.... i can recomend u this new way...


Follow the White Line
http://downloads.modlabs.net/bios/pic/4th-Method.JPG

Yup...that's great Idea tictac... but I don't know if it's work... for your Vref... (I'll try it for You...)


p/s : I'll use u'r 4th way... for my next NF7-S

dont worry hyem.... i will help u as much as i can...

250MHz here we come... hehehe :D

Weird, when I was prepping for the mod, I checked Vtt and Vref (pin1 ddr sockets) and they BOTH were the same and DID NOT track Vdimm correctly after the mod. I used the Fluke "beeper" and they were shorted together, no question of it.

Wonder if ABit made a design change in the board at some point that we dont readily see on examination?

I'm testing now with the heat spredder OFF my 512M stick....which BTW is winbond CH-5 0338WI date code....all 16 chips. The SPD on these is 8,3,3,2.0 @ 200 and 9,4,4,2.5 @217

What do others have for SPD code on HyperX3500 sticks?
You find it by using CPUZ v1.21 and go to "ABOUT" and hit "memory SPD" it will put a spd.txt on your desktop. Open and read the report. My 2x 256 have same SPD but they do 11,2,2,2 at 250, so are they BH5 or not, dunno. Guess I gotta look. It's a :banana: :banana: :banana: :banana: :banana: getting the heatspredders off.

My 2x256 KHX 3200 (with BH-5) SPD:

Frequency (MHz) 200
CAS# 2.0
RAS# to CAS# delay 2
RAS# Precharge 2
TRAS# 6

Stable at 243MHz - 11-2-2-2 - Vdimm: 3,2V - Vtt: 1,49V

Vbt when follow the Vdimm (at half of it) certainly gives better ocability in ram. This was the case when I moved from NF7 to AN7 (AN7 gives 3.34Vdimm/1.67Vbt both from the HW monitor form BIOS) my ram performed better about 7FSB more at high Volts comparing to NF7, but I wasn't able to test it with CPUinter enable because of the bug to do a direct comparison. Unfortunately never measured the Vbt (or any other value) on directly on the dimms so I don't know if indeed Vbt follows on the dimm but not on the fet on my mobo, but I will check it out.
uwackme

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So either 2x256 or 1x512 are both happiest with 1.65Vtt 3.3Vdimm but together...they want 3.3Vdimm and 1.545Vtt... weird....not 1.55Vtt...but 1.545Vtt

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This is very strange!! I will check it out on both mobos to see if there is a difference.
Cheers, really great work guys, I can't wait go home and do my measurements and stuff too :)

measure the vref from the back of mobo it move zig zag way

pin 1 on right pin 2 on left
1,3,5,7,9,11..... 1 line
2,4,6,8,10..... 1 line

Just as a datapoint... I was doing a freinds ASUS A7N8Xdeluxe. It's Vtt tracks the Vdimm regardless of mod.

I've try da 4th way,... It's safe,.... and it's work fine,... (hope it's better than other methode).