NF7 rev2 VTT mod need it so bad...

[enduracell]

thanx Stang_Man

[uwackme]

Couple things.


Remember that Vtt is the analog of VDDQ of the DDR chips themselves. You can google JEDEC and get the specs on the DDR chips and sticks.

There are 4 voltages... VDD (VDimm) the internal voltage for the DDR chip. VDDQ the DDR chip's I/O pin driver voltage which needs to match...Vtt the motherboard end of the transmission line terminating resistors voltage. And finally Vref which is to be 1/2 VDDQ.

If you examine the VMods needed for a ATI 9700pro you see all these in action... VDDQ alteration sets both VDDQ and Vtt on this video card.

How this is all set up on the NF7 I dont know. Im not gonna FK around with mine. Anytime anyone wants to send me a dead NF7 to examine I can document all this.....Ill send it back.

Also, you realise that the voltage regulator MOSFETs can be PIGGYBACKed to double their current handling. ATI in fact did this directly with the 9800XT...note the 2 rows of 4 baby-mosfets in the upper left section fo the board front. This is 8 mosfets where the 9800pro has 4 (under the little silver heatsink).

Just some thoughts.

[STEvil]

EDIT

See next post

[STEvil]

With the 8rda/3/+ all you need to do is the "VBT" mod, so maybe the VTT is linked directly to the VBT...

Its Pin 3 for the VBT, and is done in the same way as the VDIMM mod.

It may also be possible to connect the Vagp directly to the sense input (with or without cut trace.. unsure of whether it needs to be cut) if a VR isnt handy..

[enduracell]

Thank u Stevil. U rule!. So the only thing I have to do is locate the pin 3 trace (it reads 0.13v for me pin 3) and ground it with a trimmer or I have to give volts to raise the Vbt (In the picture is the mosfet leg the Ground or ir gives volt). I m kind confused if I need to give or take volts, because u saying that will could give volts to Vbt sesnse via Vagp. If I give volts to Vbt sense doesnt it lower the Vbt output? (I think it must be connect the Vbt output with Vagp, but maybe I m confused)
(at my first post actually I meant Vbt, I just haven't noticed that Winbond calls it like that the 1/2vdimm voltage).

[STEvil]

you will have to cut the trace or lift the leg and use a VR inline from the output leg of the VBT mosfet to the VBT sense.

Doing it the other way direct from Vagp would bypass the mosfet and VBT sense altogether (I said it kind of backwards before, my bad).

[enduracell]

Thank u Stevil now I understsnd exactly what has to be done. But I have one favor to ask, because I want to be sure this is gonna work as ur 8RDA. Can u please mesure the volts on third leg od the Winbond and the output leg of the VBT mosfet? My leg (on winbond because NF7 doesn't have a mosfet vbt) reads 0.13v when it gives 1.54vbt. So I m not comletely sure that if I give 1.6v on this leg will everything work ok.
Thanks again for sharing

[Hell-Fire]

Well, get to it and let us know what happens.

[STEvil]

I get 0.18v on the one leg and 0.08v on the other (VBT mosfet, center reads 1.53v) with 3.3 line @ 3.44, VDIMM @ 3.18, VBT @ 1.53.

Hope that helps

[EQuito]

enduracell,

Why is one side of the trimmer soldered to the mosfet? I thought it should go to ground, shouldn't it? or is that leg of the mosfet a ground point as well?

Nice job btw!

[STEvil]

No, you are increasing the ohm load between a measuring point and the sense point to trick it into believing it needs to put out more voltage.

[EQuito]

hmmm..., I connect one side to ground as per this guide. What am I missing?

[STEvil]

Sorry, I was thinking the 8rda method.

Same effect I believe.

[enduracell]

Thank u Stevil for mesauring ur legs
So I have to connect the 3rd leg thats reads 0.18volts with the source 1.54v via a trimmer and before that cut the trace of 3rd leg and set the trimmer to the max resistance. Thank u all guys I will try it as soon as I got my mobo of the case so to find from the back the trace that has to be cut. Thanks again and sorry for the late reply.

[STEvil]

What mod is that for??

[enduracell]

for Vbt on Nf7! Am I wrong on that? Have I misunderstood something? Sorry again for all those questions.

[STEvil]

I think so....

You should be introducing a resistant from a read point of the VBT to the sense point of the VBT..

They should both be the same voltage at stock (1.53v for me).

The pic I posted here shows where the VR would be and the points to attach it to to correctly do the mod on an 8rda+. On the NF7 its the same idea, just different points (hopefully).

http://www.xtremesystems.org/forums/...398#post383398

[Hell-Fire]

Originally posted by EQuito
hmmm..., I connect one side to ground as per this guide. What am I missing?

That works for if you decide to leave that stock resisor and solder the 1K vr in parallel with it. Then you would sodler the VR to a ground to complete the loop.

If you remove the stock resistor, you would have to solder the middle leg of the VR to the solder pad, and the outter leg to the mosfet so you can provide current through the loop for the Vdimm.

[EQuito]

Thanks for the info!

Q: what's the advantage of removing the resistor if it woks the other way which is much easier btw?

[uwackme]

Any prgress on the Vbt/tt mod yet?

[enduracell]

Ok the to controllers are deferent the picture shows it clearly. So the Vbt sense is on pin 2 and not the pin 3 on W83301R (on W83301DR-O is on pin 3 of course).
Unfortunately the Fairchild Dual N-channel mosfet (FDS6930A) blown out (the half of it) and my Vbt has been lowered even more. (this is cased by accident . I sorted out pin 4 with 3 on W83301R and the pin 2 of the mosfet got 2.5v and blown out.) Hopefully I will replace it soon with another mosfet and as soon as I found the Vbt sense trace on the back of the mobo I ll keep u posted.

[tictac]

sorry to here that enduracell.....

hope u can keep back in action

i have dead NF7-S rev 2.0 board in my room right now....

but u r in greece and i'm in Bali...

if u in indonesia... wills send u my dead board for this project...

[enduracell]

Really thanks Tictac for ur concern. Don t worry though I thing I ll manage to find the mosfet in the coming week from the official supplier in Greece. (unfortunately I can t get a sample straight from the manufacture). If I don t manage to do so, I will RMA...

[tictac]

Enduracell... just want to give my opinion

u already found 3 vbat reading on Dual N-channel mosfet (FDS6930A)
I assume the there is three reading point because... there is 3 vdimm slot
so each 1 power up 1 Vdimm slot....

What Stevil trying to said... is we need to put VR between Vbat Sense and Vbatt reading point(FDS6930A)
so if we do it this way vbat sense will assume vbat reading is much lower than it should... than it will trigger up ur Vbat voltage

we need to cut Winbond W83301R leg for Vbat sense from mobo pcb ( pin No.2 )
and connect the vbat sense directly to Vbat reading points with trimmer/pot
than that will trigger up NF7 Vbat voltage... when we increase the resistance
but the 1st thing to do... is to measure how many voltage the pin 2(Winbond W83301R) Vbat sense read... (before mod)

and if if we can get that reading.... set the trimmer to deliver such voltage to Vbat sense... then increase the resistance to get higher vbt voltage..

correct me if i'm wrong Stevil...

[enduracell]

U are correct Tictac. The readings on pin 2 of the Winbond are the same with the three pins on the Dual mosfet u had marked. Unfortunately to cut the pin 2 on Winbond is impossible cause the pins are too damn close with each others. So I have first to find and cut the trace instead of the leg...