MSI 7900GTO Vmem mod

SF3D · 10-19-2006, 01:30 PM

Default memory voltage: 7900GTX = ~2.15V
Default memory voltage: 7900GTO= ~1.82V

Only difference is these two resistors

Name: 7900gto vmem mod.JPG
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Name: 7900gto vmem mod.JPG
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Vmem mod and read point. Best method is "red", but use turquoise if you don't want to solder. (I do not recommend "blue" method. There may be problems over 1.95V)
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Name: Vmem mods and read point.JPG
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Vgpu mod and read point:
Name: Vgpu mod and read point.JPG
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SF3D · 10-19-2006, 01:39 PM

Here you can see clearly, that these resistors are replaced by MSI

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cadaveca · 10-19-2006, 02:02 PM

LoL. And they said these weren't "refurbished". that's a good indicator that they were changed to me! Love how the flux is still there too. LOL.

Garrett · 10-20-2006, 10:16 AM

Like TS said... just pencil the left one, my mem does 1810 without artifacts @ 1.95v in 3dmark05, haven't tried more but to me it's awesome at only 1.95v... that's still 0.20v lower than real gtx mem volts, and safe right?

thehellrazor · 10-21-2006, 02:51 AM

Higher vmem only resulted in lower clock for me

Tryed 2.12, 2, 1.95 and 1.89 all made artifacts on 800mhz, But on defoult volt no artifacts on 800mhz....

Nosfer@tu · 10-21-2006, 11:15 AM

Quote:

Originally Posted by thehellrazor

Higher vmem only resulted in lower clock for me

Tryed 2.12, 2, 1.95 and 1.89 all made artifacts on 800mhz, But on defoult volt no artifacts on 800mhz....

Try removing the driver and reinstalling it.

Cyba_Mephisto · 10-23-2006, 09:55 AM

Hi
I´ve never made a pencil mod, but my 7900gto doesn´t get to 800Mhz.

So my question is:
What things do I need for such a pencil-mod?

hot_fifty · 10-23-2006, 10:04 AM

a pencil and a multimeter / ohmmeter

SF3D · 10-23-2006, 11:22 AM

-Cyba_Mephisto-
Read this:

http://sg.vr-zone.com/?i=757

Cyba_Mephisto · 10-23-2006, 11:57 AM

THX, but I can´t load the pictures.

Don´t mind. That´s exaxcly that what I needed.
If somebody has an how2 with pictures please post it.
Thank you very much!

liquid51 · 10-23-2006, 04:56 PM

thanks so much for this! I was looking so hard for a definitive answer regarding vmodding between the 7900gto and the 7950gt. At the price point, and definately after reading this, the 7900gto is the choice, hands down. And so, newegg is sending me two as I type this. Hopefully i get get near the speeds of my 7900gt vmod (and with twice the ram to boot). Thanks for the post guys!

Alexandrus · 10-25-2006, 01:54 AM

Quote:

Originally Posted by SF3D

Here you can see clearly, that these resistors are replaced by MSI

Attachment 52080

Not necesarily replaced by MSI. I've checked out 3 different GTX cards, all of them have those resistors soldered on the PCB like in your pics. The only difference is the value of the resistors.

SF3D · 10-25-2006, 06:01 AM

-Alexsandrus-

Do you see the that bright stuff all over these resistors? If those resistors are original, I don't think we would see that

I'm not talking about how these are soldered on pcb and of course values are different... (this is not the point)

Alexandrus · 10-25-2006, 06:12 AM

All the cards were not moded at all, and the same soldering marks on all of them. I find it very strange.

Cyba_Mephisto · 10-25-2006, 07:14 AM

Higher voltage only results in lower clock for me.

What can I do?

SF3D · 10-25-2006, 07:45 AM

Quote:

Originally Posted by Alexandrus

All the cards were not moded at all, and the same soldering marks on all of them. I find it very strange.

Well, that's strange indeed.

Someone changed those resistors, that is sure. But was it Nvidia or MSI?

Most important thing is, that we know what we have to change or adjust, to get more voltage

SF3D · 10-25-2006, 07:47 AM

Quote:

Originally Posted by Cyba_Mephisto

Higher voltage only results in lower clock for me.

What can I do?

Tell us little more. What voltage you used?

Cyba_Mephisto · 10-25-2006, 07:50 AM

Quote:

Originally Posted by SF3D

Tell us little more. What voltage you used?

Stock Voltage:
Memory: 780MHz

@1,94V:
Memory: <700MHz

I tried new drivers, too, without a difference.

Why are 7900GTO GPUs so bad @ ocing?
Why aren´t they so good like 7900GTX GPUs?
Are they locked or undervoltaged?
Is there any pencil mod, too?

What happends, if I pencil the right resistor to 1kOhm?

Nobody an idea?

SF3D · 10-25-2006, 10:15 AM

My 7900GTO overclock well enough. 720MHz (+50MHz delta) on air.

If you pencil that right 1.2K ohm resistor--> voltage will raise. Lower resistance=higher output voltage.

Cyba_Mephisto · 10-25-2006, 10:34 AM

Quote:

Originally Posted by SF3D

My 7900GTO overclock well enough. 720MHz (+50MHz delta) on air.

If you pencil that right 1.2K ohm resistor--> voltage will raise. Lower resistance=higher output voltage.

If you want you can try this mod:
Attachment 52295

Connect those two points (red line) with silver paint or something similar. Connection must be complete (0 ohm).

You will get ~1.45V in 3D mode. That's 0.05V over default. It might help.

Thank you very much!
You´ve saved my ass.

If you no any other mod with silver paint or pencil, please tell me.

Alexandrus · 10-25-2006, 10:42 AM

Quote:

Originally Posted by SF3D

Well, that's strange indeed.

Someone changed those resistors, that is sure. But was it Nvidia or MSI?

Most important thing is, that we know what we have to change or adjust, to get more voltage

They were not MSI cards, the GTX I mean. One was XFX, one Gainward and one BFG. All had the resistors with some solder marks around them.
Anyway, I'll do a SMD change for the VMem, I want ~1.95V to RAM, which one of the two resistors should I replace ? The 1k one with a 750-800ohm or the 1.2k one with 1k ?

Cyba_Mephisto · 10-25-2006, 10:49 AM

Quote:

Originally Posted by Alexandrus

They were not MSI cards, the GTX I mean. One was XFX, one Gainward and one BFG. All had the resistors with some solder marks around them.
Anyway, I'll do a SMD change for the VMem, I want ~1.95V to RAM, which one of the two resistors should I replace ? The 1k one with a 750-800ohm or the 1.2k one with 1k ?

The 1k one with a 780 ohm.
I checked with my calculator.

Alexandrus · 10-25-2006, 11:25 AM

Thanks. Will try to find the right SMD to replace the 1k.

Cyba_Mephisto · 10-25-2006, 11:37 AM

Quote:

Originally Posted by Alexandrus

Thanks. Will try to find the right SMD to replace the 1k.

Isn´t it better to take a variale resistor?
Has the VGPU-Mod been tested?

thehellrazor · 10-25-2006, 02:40 PM

Quote:

Originally Posted by SF3D

My 7900GTO overclock well enough. 720MHz (+50MHz delta) on air.

If you pencil that right 1.2K ohm resistor--> voltage will raise. Lower resistance=higher output voltage.

If you want you can try this mod:
Attachment 52295

Connect those two points (red line) with silver paint or something similar. Connection must be complete (0 ohm).

You will get ~1.45V in 3D mode. That's 0.05V over default. It might help.

Somebody tryed this ??
I get 750 stable on the core on stock volt and cooling so would be funny to see how far the core will go with a little extra voltage