# GeForce 8800 GS/GT/GTS Voltmods



## largon (Feb 28, 2008)

Show article


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## infrared (Feb 29, 2008)

Thanks largon, very useful article indeed.


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## warhammer (Mar 2, 2008)

Nice article Largon, what benefits would this mod give me. I can push my GPU to 780 with no probs.


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## largon (Mar 2, 2008)

*warhammer*,
780MHz at stock vGPU is _really_ nice indeed, vGPU mod would allow you to push it well past 800MHz and with the right voltage I bet 900MHz could be gaming stable - assuming your card(s) are under water as well... 
Shader clocks gain from vGPU too.


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## wolf (Mar 3, 2008)

at 1.3vcore+ i hit OCP, so im keeping it under that atm, max benchable freeq's are 840/2052 core/shader. at around 1.3v, atm i run my old oc (760/1836) jsut with 1.2v as it was not completely stable before and loves some extra juice.

weird thing is i get the very low volume high pitch whine/buzz that other 8800GT owners have talked about, it did this the first day i got it with no o/c's and doesnt seem to effect system stability....should i remove all mods and RMA?


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## warhammer (Mar 3, 2008)

Thank you for the explenation largon.


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## largon (Mar 3, 2008)

wolf said:


> at 1.3vcore+ i hit OCP, so im keeping it under that atm, max benchable freeq's are 840/2052 core/shader. at around 1.3v, atm i run my old oc (760/1836) jsut with 1.2v as it was not completely stable before and loves some extra juice.


To be sure it's OCP that's limiting you measure the vGPU after the screen goes blank. When OCP activates vGPU goes to ~0v.





> weird thing is i get the very low volume high pitch whine/buzz that other 8800GT owners have talked about (...)


The buzzing is nothing to be worried about. It's the vGPU coils that start resonating at high frequencies.


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## wolf (Mar 3, 2008)

so no need to RMA at all? no sweat? cos i am a little worried....


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## largon (Mar 3, 2008)

No worries, the coils that cause the buzzing are just simple coils of copper wire, they are pretty much indestructible so resonating will not hurt the card or the components. The buzz can be irritating though. :\ 

Pretty much all high-powered video cards do it anyways...


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## wolf (Mar 3, 2008)

cheers man you are an absolute legend, for the article, the advice .... jsut cheers man


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## candle_86 (Mar 6, 2008)

largon said:


> No worries, the coils that cause the buzzing are just simple coils of copper wire, they are pretty much indestructible so resonating will not hurt the card or the components. The buzz can be irritating though. :\
> 
> Pretty much all high-powered video cards do it anyways...



my GS has yet to buzz


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## infrared (Mar 6, 2008)

Get a really quiet system, and turn the fan down on the card and i can pretty much guarantee that you'll hear a faint high pitch squeel when you open the 3d veiw in atitool. It's just that some cards are slightly louder than others.


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## albinowino (Mar 7, 2008)

First I must say this article is awesome and makes it all much simpler than reading through the massive XSF thread, thanks for taking the time to write it.  I am wondering about the reverse VMem page however.  From what I gather, this mod decreases voltage as resistance is lowered so to have the pot set up for CCW turns lowering the voltage, the pot needs to be wired differently.  Do I have it right?


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## largon (Mar 7, 2008)

*albinowino*, 
That's right. Anyways, I edited the pics for vMEM and Reverse_vMEM according to voltage change and tuning direction.


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## albinowino (Mar 8, 2008)

Excellent!  BTW I like the renditions of the wires and pots.  So much easier on the eyes than dots     I'll be trying the VMem pencil mod to see if my GT responds to more VMem.  Stock is 1.88v strangely.


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## Titus (Mar 9, 2008)

Great thanks Largon 

Nice thread ! I own a 8800 GS and i touch the limits wiyh it suddenly : i think i can push it more but not without a V-mod. I will take my soldering iron and follow your directives after a bios flashing test @ max actual stable frequencies.


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## gOJDO (Mar 12, 2008)

Very good Largon! 

But what about the Pencil/BIOS mods?

/me is making a custom water block but has no balls to do a hard mod on his GTS.


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## largon (Mar 20, 2008)

Pencil mod is not possible, and IMO the only BIOS mod worth mentioning would be a GDDR3 timing-tweak if you got the dreaded Qimonda onboard.


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## Titus (Mar 20, 2008)

largon said:


> ... and IMO the only BIOS mod worth mentioning would be a GDDR3 timing-tweak if you got the dreaded Qimonda onboard.



If someone has an idea for a GDDR3 timing-tweak for Qimonda chips for my XFX 8800 GS bios modded


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## nflesher87 (Mar 28, 2008)

any recommendations on where best to purchase a soldering iron and resistors?
I have a DMM I can borrow from the physics department here at school


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## phyx1u5 (May 13, 2008)

Hi there,
Just a query with the reverse volt mod, do you set the resistance of the resistor to minimal then turn up the resistance? or start at 50k ohms and turn down the resistance?
Also is a 1k ohm VR ok for the vgpu mod? Im not planning to exceed 1.35volts loaded
Cheers


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## largon (May 13, 2008)

_Always_ set the VR to maximum resistance. And yes, 1kΩ is perfectly good for vGPU mod.


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## Laurijan (Jun 27, 2008)

Thanks lagron for this thread and the one at xtremesystems..


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## largon (Jun 27, 2008)

Cheers!


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## Dar_T (Jun 30, 2008)

Hey largon, so I have my cards at 1.38v but every time I try to join a game in Cod4 it will use the over current protection on me. I was sort of unclear as to how to fix it in your OP. Since I have 8800 GTS and 3 points do I use two resistors? Which type of resistors (ohms). 

Thanks


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## largon (Jun 30, 2008)

*Dar_T*,
What frequency you run your card? 
What exactly happens when it crashes? *Does vGPU drop to near 0 volts?* 

Anyways, for OCP mod, you must use 3 identical resistors each rated for, say, 3000Ω.


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## Dar_T (Jun 30, 2008)

I ran them at 882/2052/1115. My computer will just shut off and vGpu does drop to 0 volts right after the crash. So I take 3 resistors, each 3000ohms, then solder it onto those three points as depicted in the picture and then leave the other end dangling?


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## largon (Jul 1, 2008)

Ok, that sure sounds like OCP in work.


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## Dar_T (Jul 1, 2008)

So, just one last thing. I solder a resistor on each of the points and leave the other end free floating. Is that correct? Also what resistor should I use to bypass 1.38v? Btw, largon, thanks for all you help. Cheers.


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## largon (Jul 1, 2008)

Err...
I'm not sure what you mean by "leaving the other end free floating"? Normal resistors have two ends and if you solder the parts on the capacitors (that have 2 ends aswell) as per the guide there _is no_ "other end" left to "float free". 

OCP mod has pretty much nothing to with voltage tolerance. If your card doesn't like >1.38v there's nothing that can be done.


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## Dar_T (Jul 1, 2008)

lol sorry I'm totally confused now. In the pic in OP it shows two lines joining between the 3 capacitors does that mean I only need 2 resistors? One resistor linking 1st cap to 2nd cap and then a second linking 2nd cap to 3rd cap? Ohhh now I think I get what you mean. You put a resistor from the brown part to the question mark. Am I right?


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## Dar_T (Jul 1, 2008)

I noticed something weird while I was testing. When both cards are in the OCP is at 1.3v but when one card is in the OCP is at 1.4v.


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## largon (Jul 1, 2008)

The red lines & circles in the pic are just for highlighting where the capacitors we're interested reside. Inside each red circle there's a surface mount capacitor and on each of them there's a resistor "soldered" to demonstrate the mod. You just need to solder a 3kΩ resistor on top of _each capacitor_. Do _not_ link the capacitors with the resistors.


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## Dar_T (Jul 1, 2008)

Doh. Should have seen that. Thanks.


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## boogerlad (Jul 17, 2008)

sorry for such a noob question, but for the vgpu voltage mod, alternativly, can you solder the middle pin on the vr to ground on the 6 pci-e power connector instead of the small point near the primarion ic? Thanks for the helpful guide! soldering to a small point like the one near the primarion ic is hard.


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## largon (Jul 17, 2008)

Any ground will do.


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## boogerlad (Jul 18, 2008)

Middle pin is connected to ground right?


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## largon (Jul 18, 2008)

In the guide pic the _lower soldering_ point is ground. In the picture, middle pin is actually connected to a point (the upper point) that _must_ be used.


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## albinowino (Aug 6, 2008)

*Mismatched OCP caps*

Heya Largon, me again with a question about the OCP caps.  One of the two on mine measured stock resistance to be 1.029K, the other 1.043K.  I triple checked to confirm.  Upon soldering 4.03K SMR's to each, the resistance now measures 660ohm and 841ohm, quadruple checked.  I recall the resistance should be identical or else the phase balance could go out of whack.  Is this normal?


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## Hayder_Master (Aug 6, 2008)

very good work largon , and very useful , thanx


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## largon (Aug 6, 2008)

albinowino said:


> Heya Largon, me again with a question about the OCP caps.  One of the two on mine measured stock resistance to be 1.029K, the other 1.043K.  I triple checked to confirm.  Upon soldering 4.03K SMR's to each, the resistance now measures 660ohm and 841ohm, quadruple checked.  I recall the resistance should be identical or else the phase balance could go out of whack.  Is this normal?


That's kinda weird 'cause the resulting resistances should be both above 800Ω. That 660Ω might indeed be a problem. 
Perhaps the other SMR took some thermal damage while soldering and it's resistance got lower?


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## albinowino (Aug 6, 2008)

largon said:


> That's kinda weird 'cause the resulting resistances should be both above 800Ω. That 660Ω might indeed be a problem.
> Perhaps the other SMR took some thermal damage while soldering and it's resistance got lower?


Oh man I hope not, haven't had problems so far with my 15 watt iron but it could be possible.  I did desolder the SMR to test its individual resistance again and it was the same as pre-soldering.  The cap could have been damaged though, don't know where I would get a replacement 

Update- this is very odd; the cap/SMR combo that once read 841ohm and I have not touched with the iron since then is now reading 664ohm and replacing the SMR that I tested onto the other cap is reading nearly the same at 661ohm.  I checked the battery on the DMM, seems okay.  I assume this would be safe to run it then?  Should they both still be above 800ohm?

Update2- okay, solved the mystery of the yoyo resistances.  When I have the positive lead of the DMM on the inside of the cap/SMR (towards the Primarion chip), I get ~840ohm on _both_.  When the positive lead is on the outside of the cap/SMR, I get ~660ohm on both.  This threw me for a loop as I thought it did not matter which lead was which on either side of the SMR.  To make matters worse this "no clean" flux is more difficult to see than rosin so there was some flux dirtying up the leads.


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## boogerlad (Aug 10, 2008)

hey largon, i got a vr just like that in the picture, but it's rated at 64 watts. is that ok?


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## largon (Aug 10, 2008)

*boogerlad*,
Heh, that "64W" is not wattage rating. It's a standard code for a certain type of VR: 
64 = 3/8" square device package
W = inline legs

"64Y" would be the same but with leg #2 (middle) higher than legs #1 and #3. 

Anyhow, the VR is fine for this mod as long as it's 500-1000Ω.


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## jeanpieterse (Aug 20, 2008)

*Hi Largon...*

Hey Largon! 

I really want to try this mod...! I've bought all the resistors..and i was ready to do it!
But my Card's PC Board is different to the one u showed..                                               I've got a XFX Nvidia Geforce 8800GS 384MB... And my chip's have different numbers..
I'm sure if i can locate the right vMEM and vGPU points.. and the two chips of interrest.. but i'm not sure on my card...

Can u help?

Thanks!!


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## jeanpieterse (Aug 20, 2008)

Hey largon,

I really want to try this mod!! But i have a problem.. I've got a XFX Nvidia GeForce 8800GS 384MB..
But my Card's PC Board is different to the one u showed.. I can't find the same chip's that you talked about.. my whole layout is different..

Can u help?

Thanks!


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## largon (Aug 20, 2008)

Can you post a picture of the backside of the card?


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## jeanpieterse (Aug 22, 2008)

hi largon,

Sorry my internet was off for a day of two.. I'v attatched two photo's..
The quality of the photo's isn't that leke... sorry about that.. I'll try to get a better one
if if u can't see clearly.. I just have to strip my PC..

Thanks hey!!


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## largon (Aug 22, 2008)

According to your pics the mod in the attached pic applies to your card. 


vGPU mod is 5kΩ VR between the points on the left side marked with red. 


If you find the pic hard to read feel free to post a macro pic of the same area on your card. Macro-mode is usually triggered by a button marked with a flower.


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## jeanpieterse (Aug 22, 2008)

Thanks for your help!! I'll check it out!!!


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## quadomatic (Sep 15, 2008)

Thanks for linking me to this thread Largon.

I bought the eVGA 9600GSO Dual Slot edition ($47 on newegg right now!!!), and so I'm going to go ahead and try this mod. Is it worth doing even if I'll be using the default dual slot cooler? Also, what variable resistors should I buy? I found these on radioshack (I could order from mouser, but with shipping it would be cheaper just to get them from radioshack)?

Errr...I'm guessing I'd need to order them on mouser.com or something. Radioshack doesn't carry resistors of the proper resistance for this.

Here are some resistors, would these work?

500 ohm potentiometer for GPU volt mod
http://www.mouser.com/Search/ProductDetail.aspx?qs=/zPWuUUsT7MBOUWHGrcugA==

20 Kohm potentiometer for memory volt mod
http://www.mouser.com/Search/ProductDetail.aspx?qs=m0BA540hBPd%2bnXSkPPJiaQ==

50 Kohm potentiometer for reverse voltage memory mod
http://www.mouser.com/Search/ProductDetail.aspx?qs=2jxZDUMdHjixhK9QkzGa9g==

4.7 Kohm potentiometer for OCP:
http://www.mouser.com/Search/ProductDetail.aspx?qs=3eDEvvxjZ0B2E6V7iiNcag==

OR (wasn't sure which to go with)

2.0 Kohm potentiometer for OCP:
http://www.mouser.com/Search/ProductDetail.aspx?qs=yLGXVRudD3ptg/FCghk3hw==

Thanks


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## jeanpieterse (Sep 16, 2008)

Hi Largon,

Tell me, In stead of using this mod what do u think about using NiBiTor..? Because u can also change your voltage on NiBiTor.. Someone said that it does't work.. But why does my frame rate change when i adust the voltage in my bios with NiBitor..?
I'm no expert on this, so just want your opinion..

Thanks!


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## largon (Sep 16, 2008)

quadomatic said:


> Is it worth doing even if I'll be using the default dual slot cooler?


The mods will _definitely_ gain you some MHz. Especially for shader domain clock which gives the most significant performance gain. 





quadomatic]Also said:


> this[/URL] for vGPU, this for vMEM and this for reverse vMEM. Note that reverse vMEM mod is useful _only_ if your card has GDDR3 made by _Qimonda_. OCP mod is not needed unless you were using exotic cooling such as phase change, etc. If you absolutely insist on doing OCP too use this set at 4kΩ.
> 
> _Before ordering the parts make sure your 9600GSO looks the same as in this guide._
> 
> ...


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## quadomatic (Sep 16, 2008)

Thanks a bunch largon! I'll be looking into this then once I get my card.


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## BUCK NASTY (Sep 17, 2008)

quadomatic said:


> Thanks a bunch largon! I'll be looking into this then once I get my card.


FYI, the EVGA 9600GSO Dual Slot has a different PCB design/layout than the single slot 8800GS/9600GSO. IMHO, it is a slightly weaker design/performance.


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## quadomatic (Sep 17, 2008)

BUCK NASTY said:


> FYI, the EVGA 9600GSO Dual Slot has a different PCB design/layout than the single slot 8800GS/9600GSO. IMHO, it is a slightly weaker design/performance.



Crap...does that mean I won't be able to volt mod it? Or that I would have to figure out how to (might as well mean I can't...or maybe I could)?


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## DOM (Sep 18, 2008)

quadomatic said:


> Crap...does that mean I won't be able to volt mod it? Or that I would have to figure out how to (might as well mean I can't...or maybe I could)?



just take the cooler off and take some naked pics of it like I did on the Palit 9600 GSO thread those are my pics if you didnt know, largon know his stuff


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## BUCK NASTY (Sep 18, 2008)

quadomatic said:


> Crap...does that mean I won't be able to volt mod it? Or that I would have to figure out how to (might as well mean I can't...or maybe I could)?


I have 2x 9600GSO dual slot's folding 24/7 and they score about 5-10% lower than the 8800GS. If there is a volt mod that would help the shader output, I'm onboard! I just ordered 2 more 9600GSO single slot's, as they are identical PCB to the 8800GS, thus better performance.


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## DOM (Sep 18, 2008)

BUCK NASTY said:


> I have 2x 9600GSO dual slot's folding 24/7 and they score about 5-10% lower than the 8800GS. If there is a volt mod that would help the shader output, I'm onboard! I just ordered 2 more 9600GSO single slot's, as they are identical PCB to the 8800GS, thus better performance.


yes there should be a volt mod just post some pics for largon he should know what you need to do

cuz the shaders run off the core volts  

I was getting like 6-7k with one card but im never on vista that much so thats why i havent folded in a while


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## quadomatic (Sep 18, 2008)

DOM said:


> just take the cooler off and take some naked pics of it like I did on the Palit 9600 GSO thread those are my pics if you didnt know, largon know his stuff



Cool. I probably won't receive the card till some time next week though (paid newegg by money order, proly will end up shipping by monday or tuesday next week, so i'd get it by next friday). If pictures haven't been posted by then I'll try taking the cooler off. Hopefully it's not an incredibly difficult task to put take off and put back on. It wasn't real difficult with my X850 Pro, but then, that wasn't a dual slot cooler.

Despite all the relatively risky (while actually not very risky at all) modding I've done with my current system, it seems to have paid off fairly well (Pentium Dual Core E2200+fsb locked motherboard+2GB Ram+HyperTX 2 Cooler for less than $100, cpu overclocked to 3Ghz by BSEL and vCore mod). This will be a nice cheap addition, proving that you can in fact play games on a computer well for very, very cheap.

If I can handle Grand Theft Auto IV in November on my system with high settings, no AA at 1280x1024, I will be incredibly pleased.


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## quadomatic (Sep 23, 2008)

My 9600GSO is supposed to come in this Thursday. I'll try to get pictures posted then.


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## quadomatic (Nov 1, 2008)

Hey all, life has been fairly busy, and I was a bit fearful of taking off the cooler from my dual-slot eVGA 9600GSO. But, since I don't have a whole lot of time for gaming at this very moment (hopefully that'll change soon) I pulled my 9600GSO from my computer to take the cooler off and take some pictures. I'm running on my Intel integrated GMA950 right now...yikes.

I tried to take as good pics as I could. The images are fairly high resolution (3072x2304), and in total all the pictures weigh in at almost 20MB, so I zipped them up and uploaded them to filedropper.

It seems like I could overclock this card quite a bit. Without the volt mod, it runs at 752 mhz core/1806 mhz shader/1050 mhz memory. When I took the cooler off I found that the memory chips are Samsung, not the qimonda chips that were mentioned as being questionable earlier (though I don't know anything about the Samsung chips).

For $34, it definitely seems like I'm getting my money's worth. Fallout 3 runs beautifully, as does most every other game I've tried (Crysis is a bit questionable, but that's to be expected).

So, if someone could have a look at these pictures and tell me what I can do for a volt mod, I'd appreciate it:

http://www.filedropper.com/9600gso

Thanks a bunch!


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## quadomatic (Nov 7, 2008)

So...has anyone taken a look?


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## quadomatic (Nov 10, 2008)

bump?


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## infrared (Nov 10, 2008)

Google !!

http://www.xtremesystems.org/forums/showthread.php?t=196707

Since this thread is for 8800 series graphics cards, you would have recieved a response faster by making a new thread


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## quadomatic (Nov 10, 2008)

Ummm, yeah...

The reason I posted the pictures is because the eVGA card doesn't have the same PCB layout as any of the other cards out there, which is why I needed someone to look at the pictures I posted of my card.

Since my card has been sitting outside of my PC for about a week, and I've been using my integrated intel chipset for vga, if I thought finding a solution was as easy as Google, I would've found it already.


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## infrared (Nov 10, 2008)

Ok, my bad. 

Lemme take a look. The voltage control chips should be pretty much the same.

edit: your link doesn't work


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## quadomatic (Nov 11, 2008)

infrared said:


> Ok, my bad.
> 
> Lemme take a look. The voltage control chips should be pretty much the same.
> 
> edit: your link doesn't work



DARNIT

I'll find a better host.


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## DOM (Nov 11, 2008)

quadomatic said:


> DARNIT
> 
> I'll find a better host.



http://www.techpowerup.org/

File extensions allowed: gif, jpg, png, maximum size: 2 MB


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## quadomatic (Nov 11, 2008)

There, they've been uploaded to Imageshack...I had to reduce quality of the images from 89 to 85 in GIMP though.

I do wonder if the "N88GT-LF REV: 1.2" printed on the front of the PCB would help at all.

Back:





Zoomed (Left, Center, Right):








Front:





Zoomed (Left, Center, Right):


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## infrared (Nov 11, 2008)

Interesting lay-out.

The voltage control chip (for the gpu at least) is the RT8802A chip on the front-right of the board.

http://www.alldatasheet.com/datasheet-pdf/pdf/207883/RICHTEK/RT8802A.html

I'll have a quick look through the datasheet, but it's been a long time since i did electronics at college. Anyone feel free to jump in if you figure it out.

EDIT:

If you have a conductive pen you could do a VID voltmod which would be quicker and easier than using a pot. See pages 5-6 for the VID voltage table. Basically you set the gpu voltage by removing SMR's and bridging gaps.


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## quadomatic (Nov 11, 2008)

infrared:

Thanks for taking a look. I really appreciate it.

If anyone needs better pictures of any specific part of the pcb, let me know.


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## quadomatic (Nov 11, 2008)

Hmmm, I don't really know what the VID-Table says. Is it just that if there's resistance on some pins and none on others then the voltage will be different? So, I'd match up the resistor placement with the 0's being no resistor, 1's meaning yes there's a resistor, and the output at the end of the chart is the voltage I'd get?

If I took too high of a voltage, then wouldn't I be kinda screwed since I wouldn't be able to put the resistors back?

WOW, the picture makes those soldering points look big. Those resistors are absolutely tiny. I'm not sure how I'd go about removing those.

Just as a size comparison, I put a penny next to the chip. Those points are TINY.


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## infrared (Nov 11, 2008)

You've got it. They basically ground out the pin, which would be a 0 on the VID table. If we can find a vmeasure point for the vgpu we can verify that.

To remove them you can heat them with a soldering iron while lifting them with a fine pair of tweezers. I used to just crush them with needle-nose pliers lol. Use conductive ink to re-connect the pads. To make it more permanent when you have the desired voltage you can spray over the area with a conformal coating to protect it. Comes in an aerosol can you can get at any electrical shop.

Ok, working from the table, if you 'open' the connection (1), the effect would be:

VID 6 = +0.00625
VID 5 = -0.01250
VID 4 = -0.40000
VID 3 = -0.20000
VID 2 = -0.10000
VID 1 = -0.05000
VID 0 = -0.02500


Hmm, I'll drop Solaris17 a PM. He should be able to help figure out a bit more.

I'm off for the night (3:10am here lol). I'll take another look tomorow after work. Hopefully we can figure out a Vmeasure point, and then maybe the vmod for the memory.


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## quadomatic (Nov 11, 2008)

Cool, sounds good.

Just to check, how are we able to tell which side of the chip is facing "up", so we know which pins are the vid pins?

Also let me know if you need me to read off the names on any other chips. I notice the names on the ones on the back aren't that visible.


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## infrared (Nov 11, 2008)

Because of the block of smr's. The other sides have capacitors which aren't used for setting VID values.

I'm 99% sure, but i'll double-check tomorow with the datasheet.


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## dd051 (Nov 15, 2008)

Infrared et al : any ideas on: 

http://img360.imageshack.us/my.php?image=1002795textkc5.jpg
http://img509.imageshack.us/my.php?image=1002796textbe7.jpg


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## quadomatic (Nov 16, 2008)

I'm not sure what the default voltage of the card is. Do you know?





I'm looking at that picture to determine default voltage and which resistor connections go to which pins.

It LOOKS like VID1 and VID6 are the only pins that don't have resistors, so those pins aren't connected to anything (meaning 0 I guess?), so I guess the default voltage is 1.11875V.

So, it looks like in order to raise voltage, do you not remove resistors and bridge gaps, but just remove resistors and leave gaps? That appears to be the way it is, since VID1 and VID6 lead to pads that aren't connected - the traces just lead to solder blobs that would hold a resistor, but those blobs aren't connected.

How much could i raise voltage to? Would 1.3V be safe on a dual-slot air cooler?

I could hit 1.31875V by simply removing the resistor on VID3 (on the chart, it has 1's accept on VID3, VID1 and VID6 for that voltage. So would I be correct in saying that 1's are connected, and 0's have gaps that aren't bridged?

Would removing resistors and bridging gaps be safer? That way I'd be able to test a different voltage that would be lower. I wouldn't be able to attach resistors...are they necessary to make sure I don't fry the chip?

I think this is the proper layout. I labeled the pins as well as the resistors they trace to:


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## quadomatic (Nov 17, 2008)

Someone else did a pencil mod by following the FB pin to the resistor it connects to and shading the resistor. It increased the temperature by 6 degrees Celsius. Based on the change in resistance after doing that, I'm guessing the voltage after the mod was 1.165V. Raising voltage to 1.32V might be problematic.

So, maybe I should shoot lower?

Or wait...I don't think that would work. The idea isn't to shade over the resistor with the VID resistors but to remove them and make a gap in the connection. Right?


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## infrared (Nov 17, 2008)

yep basically.

We really need to find a vgpu measure point before you start playing, but tbh i have no idea where to start looking.


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## quadomatic (Nov 18, 2008)

I see...

http://www.xtremesystems.org/forums/showthread.php?p=3436333&posted=1#post3436333

Should probably look at that thread. panzerchaos47 has 2 9600GSO's that he's testing with. GPU0 has no pencil mod, and GPU1 was modded using the FB pin.

He labeled a point he's attempting to use to measure voltage:

http://i256.photobucket.com/albums/hh166/hitokirixii/9600gsomeasurepoint.jpg

I don't think that's likely the actual point though, and neither does he, since it registers 1.25V on idle w/out pencil mod, and BIOS limits voltage to 1.1V by default, and based on the VID diagram I figured the voltage is 1.11875V.

Either way, it seems to accurately predict the change in voltage.

On idle, the card without volt mod is 1.25V, and with volt mod, is 1.32V (this is just the READING, probably not accurate voltage, but that shouldn't matter since we know default voltage...aren't we just concerned with voltage change?)

Based on calculations of resistance changes measured with the multimeter, the voltage change should be about +.07V...and 1.32V-1.25V=.07 So....I guess that point is at least reliable for measuring CHANGE in voltage.

Does the change in voltage using the FB pin depend on the thickness of the shading over the resistor?


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## quadomatic (Nov 18, 2008)

I decided to try the FB volt mod. It doesn't seem to be producing the desired effect. I had to lower clock speeds back on the memory. Maybe I shaded to thick? It seems like the gpu is hotter than it used to be...is 64 odd?

Maybe because I didn't reapply thermal grease properly? I just shaved off the dried paste that was on the heatsink before and threw it back onto the core. Probably has some burn in time, but still...

Maybe the added voltage requires a better cooler because of the extra heat?


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## quadomatic (Nov 19, 2008)

I took the cooler off and looked at the core, and I found that the thermal compound wasn't exactly working as I planned...so yeah. Looks like reapplying thermal compound is a _little_ important. It was all dry and bunched up.

Regardless, I ordered an Accelero S1. I'm going to attach that to the card, with a 120mm fan ziptied to it. That should help significantly.


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## infrared (Nov 19, 2008)

The accelero comes with some really nice thermal paste pre-applied (AC MX-2), but if you need to remove it again, get a tube of it and apply it fresh. I would also highly recommend getting some Arcticlean.


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## quadomatic (Nov 21, 2008)

Good to know.

Now I just have to wait till...Tuesday for it to show up. Dang UPS is slow. Everyone should just use USPS (in the United States anyways...). Saves a lot of cash and its wayyyyyyyy faster. Would've been about $5 flat-rate and it would've gotten here in 2 days.


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## maynardx (Nov 27, 2008)

Hello everyone
As far as I'm newbie in electronics, I'd like to ask You, which resistors exactly should I buy for EVGA 8800GTS KO Version? I will appreciate all Your help Guys.


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## quadomatic (Dec 4, 2008)

infrared said:


> yep basically.
> 
> We really need to find a vgpu measure point before you start playing, but tbh i have no idea where to start looking.



http://www.xtremesystems.org/forums/showthread.php?p=3472814&posted=1#post3472814

Someone has tried removing the resistors that were connected to the pins for voltage, but it made absolutely no change. Are we sure those are the voltage pins? Is it a different side of the chip that's for voltage?


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