7900 GS / GT Volt Mod

This mod applies to nvidia reference PCBs (XFX usually does not apply)

XFX New PCB VMod Here

Materials...
Conductive ink
lead pencil (6B Work the best , Any will do)
Some good music
Chips and dip :cool:


Heres the backside of the card with the mod spots marked off

http://img163.imageshack.us/img163/1...eofcardbo9.jpg

Take your conductive ink and draw a trace connecting these three components

http://img163.imageshack.us/img163/6326/gpuvmodvo2.jpg

Close up of Memory Resistor Shading mod

http://img516.imageshack.us/img516/2...esistorci2.jpg

AND, For those of you with stock cooling or halfway decent air cooling

Here are smaller vmods , same traces though

on stock I wouldnt recommend going above 1.3v unless you have extremely low ambient temps

http://img527.imageshack.us/img527/7420/150vmodgl7.jpg

Heres The Cooling im using Gets me 32c idle and 34c load with 25c Amb
http://img475.imageshack.us/img475/6104/1002217sp6.jpg

Results so far :D

http://img201.imageshack.us/img201/4462/untitledgi2.jpg
http://img201.imageshack.us/img201/853/110kam3fs9.jpg

Now Give yourself a Pat on the Back and have a nice Sandwich
http://img258.imageshack.us/img258/1...paratusys6.jpghttp://img258.imageshack.us/img258/4...andwicher5.jpg

Thanks for reading , Please leave feedback :D Also if you tried it please share your results :)

Very cool!

I've got a GS right now with stock cooling, And I may be getting a new Air HS \ WC setup... What voltages would you suggest for Air? 1.4?

Also, what are the specific diagrams for Mem volt mods?

what vmem are you using to get 1000?

Uff 1Ghz mem, how are you cooling the samlle chip?

Getting a FC79 too, so ill be doing the big mod too.

Its under the EK Waterblock , Im using about 2.3 (if im not mistaken) on the memory

I have to cool about 4 different chips on the top of the card now , one of them never used to get hot ????

haha its tt grp of ics at the vmem mod there right? cool them down to get less artifacts in 3dmark

Quote:

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Originally Posted by Cupcake

Its under the EK Waterblock , Im using about 2.3 (if im not mistaken) on the memory

I have to cool about 4 different chips on the top of the card now , one of them never used to get hot ????

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Im a bit unsure now, are all the chips that have to be cooled under the FC79?

Just got mine today YAY! :D

How much cooling does the mem chip need?

(I assume its the one with "6549CBZ P548C4D" on it)

http://img516.imageshack.us/img516/2...esistorci2.jpg

I have some Zalman VGA sinks, would one of them be enough?

http://www.levicom.de/xilence/en/xpram.htm

It would most likely be enough , I have some pretty cheap copper sinks on mine and they get pretty damn hot but not hot enough that im worried

I run 2.3v BTW

I would say a zalman sink would be enough as long as you have some airflow around it

Ok, nice.

But just to get it allll straight.
All the chips that have to be cooled, get cooled by the FC79, exept the mem chip.

And am i looking at the right mem chip? the one with "6549CBZ P548C4D" on it?

that depends.... whats the FC79 ? lol

but actually I use 3 ramsinks on mine

I will get pics of where they are in a minute

Here you go mate, I put little comments about what im using

Id ask someone with more experience which chips actually need to be cooled

http://img243.imageshack.us/img243/2...0gsbacklt8.jpg

I thougt you use a EK FC79 waterblok?

Many thanks, a very usefull picture :) Ill put sinks on all of them :D

Hm, maby the Xilence sinks are not even enough

I just didnt know it was called the FC79 :)

Even the Rev2 boards still have that heat problem by those chips but not as hot as rev 1

im guessing mines a rev 2 cause I only got it about a month ago

Can you clock your core higher?

mine clocks 630 on default voltages

EDIT: ops stupid me, 500 is the default

so how high can you clock your core with the volt mod?

oh , 720 stable

I hit 850 once but it froze up in seconds

wish I had a screenie of that :D

Quote:

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Originally Posted by Cupcake

Here you go mate, I put little comments about what im using

Id ask someone with more experience which chips actually need to be cooled

http://img243.imageshack.us/img243/2...0gsbacklt8.jpg

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I am looking all over Denmark for a decent pencil, and i think i found something.

But befor i start, i just wont to know, it the chips that heat op at the buttom of the image, do they only heat up when you do the memVmod?

I think the ones at the bottom of the picture get hot from the mem mod and the top ones get hot from the core mod

Im not sure so feel them after doing your mod

hey i cant find here a condactive pen :( if i do the mod and just wired the will it work ? i don't have any problem to solder a wire on the :D

sure

thanks man i have already soldered it :D tomorow i will try the 1,4 mod i just hit 620/900 memmory on 2.1 core on 1.3 not bad :D it gave me 23.174 on 3Dmark 03
and the temps i hink they are good 45 idle 58 on load with one zalman 900cu led (i think this is the name)

thanks again :D

ok i need some help now :) i set 1.4 the Vcore and 2.4 the Vdimm how much up can i go now safe i have 660Mhz on the core and 1000Mhz on he ram i have hynix chips can i raise more voltage on the rams chips is it save to go above 2.4 Volts ?

2.4v is WAY TOO MUCH. i wouldn't go higher than 2.2v or so.

the 7900 isn't memory bandwidth starved anyway, so raising memory that high would net you hardly any improvement.

Also, if you raise vram to 2.2v or beyond, you should put a heatsink by the ic next to the mod, because it will get very hot and cause instability.

as for core, what temps are you getting under load? what are you using to cool it? if you have good cooling, you can give 1.45v or 1.5v a go.

i have put some thermaltake ram heatshinks on the mosfets and the regulators on the back of the card on 2.2V on memory i couldn't go more than 900Mhz on 2.34 exacly i can hit 1Ghz so is it so terible ?

for the core under load i'am having about 60 degrees celcius for the core coolin on zalman VF900-CU LED but i'am going to put a Wb on her :D
you scared me i can say that :) i'am runing @ 2,3V now on the ram but on 1000Mhz i am having delta mismach on atitool :(
and the resualts are :

about 23K on 3D Mark 03 with my E4300 @ 3Ghz an my rams @ 1Ghz 4-4-4-14 i need a new psu tho :D

http://img249.imageshack.us/img249/2657/52003946xk7.jpg
http://img177.imageshack.us/img177/8797/50859845bh4.jpg

do you have the fan on the vf900 on low or soemthing? I could have sworn I had much better temps than that when I had one on mine.

As for high speed ram, do some testing at 800mhz, 850mhz, 900mhz, and 1000mhz at your current core clock. You should see that the difference isn't so great. You should focus more on getting core to 700. Also, if you wish, you can fiddle with the geometric delta. I was able to run mine at +60.

the fan of the cooler is powered from the card i changed the conectors on @ 2D is running @ 25% on 3D @ 100%
you are right about the mem i did't noticed any difrent but i want the 1Ghz for the number call it fetish :D

as for the core i read that 7900's are not so hapy with 1,5 volts and the blow the core so i'am afraid to set 1,5 i might to a mod with a jumper tho and if i want to set the core to 1,5 just switch the juper

1.5v to core with good cooling is much safer than the 2.34v you're pushing to the ram.

yes but the card runs hot for now is it safe to set the voltage @ 1.5 V
the ram voltage now is 2.3V not more not les the card runs good win no artifact @ 660/1000

what you sugest is it save the 1.5V on the core with my temps ? note that outside we have more than 40 C and i can't have the ac 24/7 open :D

Quote:

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ziddey
Also, if you wish, you can fiddle with the geometric delta. I was able to run mine at +60

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mine delta is set to 20 (NiBitor) how soud i set it 20 + 60 = 80 ?

Has anyone else ran into OVP trouble with their 7900GS? If I try 1.35V, the moment the card switches to 3D mode, I get a black screen. Below 1.35V, things are fine.

Does anyone know which SMC need removed for OVP bypass?

Cheers!

I take it you don't have a reference board, or at the very least, are not using the common ink method?

Also, can you actually measure that in 2d mode, it's a different voltage? I haven't seen a 7900gs (at least reference pcb) have the components to switch voltage from 2d to 3d.

Im using a pot connected using this pic as reference:

http://resources.vr-zone.com.sg/Sham...s/79gtvmod.jpg

Reference design.

To be honest, no, there is no voltage change from 2D-3D, but its when the clockspeeds switch from 2D to 3D mode...same thing, more or less.

I chose not to use a 1.5V forced mod, I like having the element of control over my mods and voltages :)

K

Pic taken from Shamino/VR-Zone

Hmm, well if you're willing to go the switch route, you can still have control, and have switches that flip open +0.1v, +0.2v, and +0.05v, so by varying the switches, you can get your control from the baseline 1.2v.

edit: just did a google search for 7900gt ovp and found a lot of results. http://www.xtremesystems.org/forums/...ad.php?t=92874 as a place to start.

but that's only if you don't consider my idea, although you'd be limited to combinations of the 3 increment amounts

hope this helps :)


edit again: http://www.xtremesystems.org/forums/...d.php?t=103890 that was something I've always been interested in myself, but too lazy to get around to. if once you've found your satisfied overclock, but want to keep low 2d volts, that's the method for you :)

Thanks for the links :D I have some insight now into why the pic cupcake posted works :D

I might play with the BIOS to have a 2D-3D voltage switch in future. Shouldnt be too difficult.

thanks!

Kenny

cupcake? i'm sure you know this already but just wanted to make sure by saying that you need to add components to allow the vid switching to work. :) good luck and post your results :)

I see that everyone is still loving the cards. I've got some here aswell, especially 7900GS cards.
They are quite amazing. If you OC them with 1.55v and some more voltage to the memory, they will easily own a 7900GTX for just over $100...
Really a good card to hold over till HD2950 or 9800gtx! :clap:
But the results here are very impressive! :shocked:

any hard mod for the mem vr or something i flashed the card with edited bios so i need somthing stable on the mem :P

is this going to work or i will fry my vga :confused:

that'd work but you will very very much so want to throw a sufficient heatsink on that ic next to it.

I have coolers on the card that'a not the problem ;)
are you sure that this will work i don't wana fry my card couse i canot buy a new one :(

this is my card ;)

http://img234.imageshack.us/img234/1...im1400ptb5.jpg

soldering a vr is no different than shading with pencil. if it were to break, it'd be from the overvoltage of course.

the card isn't bandwidth starved, so you dont need to push ram that much.

with a pencil I got up to 2.8v

I have to be careful when penciling my cards

ziddey thank yoy very much i'am going to buy some vr tomorow or the day after i will post my results

Cupcake i want the vr couse the boded bios on the vga and the pencil on some days is gone so the voltage is lower day by day :)

hello boyz !

Thanx cupcake for a nice piece of information about 7900vmod ,

I got very sad problem :
I'm on rev.1 asus 7900gs "asustop" with 1,2 ns mems ... whatever which kind.
My target was 700 on core , but it seems to be no so :banana::banana::banana::banana:in' easy, maybe even
unpossible
Core is unstable on 670 mhz even @ 1,55 v [checked] , a there is no visible diferences betveen 1,4 and 1,55 v [670mhz is last stable config every time]

I should mention that all "chips" on the back side of pcb are properly cooled by bga radatiors

Core and mems are cooled by zalmam VF700-Cu , and Arctic silver 5 grease. max core temp is under 70C ...

Maybe some chips on the front side should be cooled ? i got some radiators avaible , but im not sure which could be taped :)

any ideas ? or my 7900 core is over @ 670 ?

Might well be temps. Can you get access to a waterloop or a chiller?

dnarts, are you able to verify that the voltage is indeed increasing with each mod you apply?

1.2ns ram means 833mhz. that's faster than the hynix 1.4ns that came in most other boards.

indeed, how do your temps look. have you tried reapplying thermal compound and remounting?

Quote:

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Originally Posted by K404

Might well be temps. Can you get access to a waterloop or a chiller?

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Negative. Only some some fans ,

Quote:

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Originally Posted by ziddey

dnarts, are you able to verify that the voltage is indeed increasing with each mod you apply?
1.2ns ram means 833mhz. that's faster than the hynix 1.4ns that came in most other boards.

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If after whole mod its 1,55 [verified] , I'ts quite possible that voltage is indeed increasing in each mod.
True , I'll downclock them to optimal rates afterall

Quote:

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Originally Posted by ziddey

indeed, how do your temps look. have you tried reapplying thermal compound and remounting?

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Affirmitive. Already reapllied . I also reapllied conductive inc yesterday once again to make sure.

My temps seems good too : about 67 C on load , other components are warm , but not hot , as I mentioned , I've applied some bga radiators on them ...

Nominal voltage on core is about 1,54 - 1,55 v

edit : i didn't do nothing to cool front side of PCB , maybe some suggestions about it [of course there are radiotors on mems]

680 is pretty respectable as it is already. I'd probably stay on 1.45v, especially with the vf700cu. 67'c isn't bad at all, but compared to water where I never see about mid 40's under load, it's still pretty hot.

when I was on vf900cu, I was also below 50'c with 1.5v. i apologize for not having much experience with those temps and the voltages to know if it's a problem or not. i did run 1.4v with stock cooler and had temps in the 80's. my o/c was around 650 or so iirc.

i'd probably stick with the 680 core and fiddle with geometric deltas. maybe you could squeeze a little more performance from there.

Quote:

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Originally Posted by ziddey

680 is pretty respectable as it is already. I'd probably stay on 1.45v,

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maybe you are right , but 700 is so nice piece of number :)

Quote:

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Originally Posted by ziddey

i'd probably stick with the 680 core and fiddle with geometric deltas. maybe you could squeeze a little more performance from there.

---

what geo delta are u using ?

What would you recommend the max voltage be for a 7900GS cooled by a V-1 Ultra? Also, where could I get conductive ink? When shadding with the pencil, you just shade it until both sides are connected?

Looks like I should go out and buy a multimeter too.

You can get ink from those circuitwriter pens, or from your auto parts store (some walmarts too). From auto stores / walmart, you'd be looking for rear window defrost repair kits. It comes with a little container of copper ink.

I'm not sure what a safe max would be. I know of many people running 1.55v, but I've also heard of a few cases of degradation as a result of it. I've been running 1.5v since January on a mcw60 waterblock, and my temps never exceed mid 40's under load. Haven't had a problem yet.

I'd probably personally stay with 1.5v as a max on good air. I know some higher end 7900's switched vid to 1.45v in 3d mode iirc (I know some switched to 1.3v only though), so I imagine that should be ok. Then again, they switch back down for 2d...

As for the ram, right, you shade both ends of the resistor. By doing so, it's like creating a parallel path, thus lowering resistance. A dmm would definitely be extremely wise. However, that said, the 7900's aren't really bandwidth starved, and it's really not worth the effort and risk in overvolting the ram. But if you do, make sure to cool the ic next to where you shade the resistor. It can get extremely hot and lead to instability / abnormalities.

How should I cool the IC? From what I've read you can mount two fans on the V-1 Ultra, one on the back and one on the front. I don't know if it would cover the IC though. I just ordered the V-1 Ultra today. Also, when he says "anywhere from 2.0v to 2.6v" how is this determined?

everything ok with me :up: i soledred the VR in pareler with the resistor for the mem and it's working great :) the Vr was a 10 K pot trimer
KoolDrew that's how i am cooling this card ;) plus an 80mm fan on top of them :cool:

http://img167.imageshack.us/img167/1421/hpim1405ui2.jpg

When I get the V-1 Ultra I will be able to get a better idea on how to properly cool it. I think I'll just start with 1.4v and then go up to 1.5v. If that works well maybe go to 1.55v, who knows. :P

Just to let you guys know , I will be soon selling my pair of Vmodded (1.5 Core 2.35 Mem) Cards with EK FC79 Blocks on them.

Just wanted to give you guys a heads up if you have any final questions before I get rid of these

PM me if you have some questions

http://aycu26.webshots.com/image/222...0241850_rs.jpg

I guess the RAM chips on my card suck. Bumped voltage up to 2.18v (tested with a multimeter) and couldn't get even a single MHz faster than I could with stock volts. Could not having cooling on the IC's regulating the memory voltage have something to do with it, or do my chips just suck at overclocking?

My core increased from 564 to 685 with 1.507v though (again tested with a multimeter).

what's your ram running at currently?

Quote:

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what's your ram running at currently?

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745. It was running at that before the volt mod as well. Got it up to 2.18v (tested with a multimeter) and try 746 and my PC just freezes and has lines going across the screen. Perfectly stable at 745 though. Even if my RAM just sucks at overclocking, I'd think I would at least get a little more with added voltage, but I guess not.

I tried this on my 7900GS and it worked perfectly. On my 7900GT however, it doesn't seem to work. Multimeter still reads 1.2V when using conductive ink on the 7900GT.

Does this not work on all cards?

Quote:

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Originally Posted by NJDevilsFan21

I tried this on my 7900GS and it worked perfectly. On my 7900GT however, it doesn't seem to work. Multimeter still reads 1.2V when using conductive ink on the 7900GT.

Does this not work on all cards?

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probably a bad contact

dose anyone know a point in this card to take 5Volts ? i wan to put a thermometer on her but it's 5 volts

Quote:

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Originally Posted by SaII

probably a bad contact

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Yeah you were right about that, got it worked.

Does anyone have insane memory on their 7900GS/GT? On my older XFX model, and newer BFGOC model, they use different memory (XFX uses some kind of Samsung memory, and I forget what the BFG used), but both are hitting 900MHz (1800MHz DDR) stable at the default 2.0V - and I'm actually wondering, has anyone ran speeds like this over an extended period of time and not had their memory fail? (I do use RAM sinks by the way)

i'am having 1010Mhz (2020Mhz DDR) rock stable on my evga 7900Gs with 2.2 Volt's ;) more than a month now and the pc is on 24/7 ;)

I tried to vmod my EN7900GS, i used some info from t024484 in this thread http://www.xtremesystems.org/forums/...=7900+volt+mod ...so thanks for the info :wave:

with vGPU=1,789V, vMem=2,4V, OCP mod and modded the switching ferquency I could reach 815MHz for GPU and 1075 for the memory - benchmark stable
the card was cooled by Accelero S1 and 2x120mm Fans and some homemade heatsinks

here´s some fotos from my mod, not so clean as others but works fine :)

http://lh3.ggpht.com/The.0Rol/SMrHHp...0/P9050089.JPG

http://lh5.ggpht.com/The.0Rol/SMrF5g...0/P9050084.JPG

in our town it´s hard to buy VR, so I used normal rezistors :rolleyes:

Very nice clocks - gratz. Any scores? Voltages are quite high - card may die one day :D

thanks man :)

here some crapy results

3D Mark 05
http://lh4.ggpht.com/_Y4dLpEskwGA/SM...0/05record.JPG

3D Mark 06
http://lh4.ggpht.com/_Y4dLpEskwGA/SM...3d06record.JPG

3D Mark 03
http://lh4.ggpht.com/_Y4dLpEskwGA/SM...0/03record.JPG

Aqua
http://lh6.ggpht.com/_Y4dLpEskwGA/SM...aquarecord.JPG

need more voltages for the core...maybe 1,9V would be good :ROTF:

tommorow i will use my new homemade WB so i would see how the temperatures are...if i can use more voltage