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GTX 780Ti Hard Mod For Voltage Control
Special Thanks to@FtW 420For His Help With The Mod and Making This Guide Possible

DISCLAIMER
THIS GUIDE IS WRITTEN TO USE AT YOUR OWN RISK. DOING THIS MOD WILL VOID YOU WARRANTY AND COULD POSSIBLY DESTOY YOUR CARD. THIS WAS WRITTEN TO THE BEST OF MY KNOWLEDGE AND AS A GUIDE TO ASSIST YOU IN YOUR OWN ADVENTURES INTO UNLOCKING VOLTAGE.

I did the volt mod on a EVGA GTX 780Ti reference this guide will show you how to test your card for the correct ohm variable resister if you are wanting more voltage then just a regular resister.
There are 2 ways to mod the card first is just a resister with a exact ohm soldered which is one of the easiest to do. The other is a variable resistor which does require more soldering skill and a lot more dangerous as far as destroying the card due to pulling the points directly off the chip.

Voltage Read Point

Below are the points for voltage reading. Since this is hardware modded you will not see the voltage through software such as Precision X or MSI Afterburner. The way to read the voltage will be by using a multi meter to get your readings.


Solid Resistor Mod

There are two points on the back of the card. Shown in the pic below. The points if are right next to the two resistors attached to the board. The later model cards do not have solder already on the points there are a orange looking color and will have to have flux added and some solder put on before you actually start soldering the resistor on. The first batches actually have solder already there so all you need to do is add your flux and go ahead and put your resistor on.


You will solder a resistor between those two points. Different ohms will give different voltages. The voltage it will give can be adjust through Precision X. So 150 ohm in my study gave me 1.268 v reading though a multi meter. So with Precision X volts at 1.21 this is the voltage I get in the image below.

So if I drop the volts down in Precision X to lets say 1.1 v. I would have a reading of 1.158. You take the 1.21 volts in Precision X get your voltage reading with your resistor which in the scenario is 1.268 (VOLTAGE READ OUT ON CARD) - 1.21 (PRECISION X SET VOLTAGE) = 0.058 v difference so you just add that to whatever you set your voltage to in precision x to get a rough idea of the voltage being used. Each resistor offers different voltage increases. Below is a small table of the resistors I used which were available at the
local electronics shop. Feel free to explore more options and let me know the findings and I will add it to the table.

RESISTOR VOLTAGE
150 ohm = 1.299 increase of .177 to any voltage set in precision x
220 ohm = 1.254
330 ohm = 1.24
470 ohm = 1.232

As @pharcycle and a few others had pointed out this could also be done using a dipswitch for the mod with this one also so you would have varying ohm resistors at the flip of the switchs.



VARIABLE RESISTOR MOD


This mod is a little more dangerous as in the chances of destroying your card greatly increase. You will need a muli meter where you can test the resistance of the point on the card to figure out your correct ohm variable resistor used.

The above picture is for a Titan but the TI is the same except for the ohm resistor used. Test the point on your card to verify that the ohm resistor you use is correct. I test the point with my multi meter on my card and it test at 1002 ohm so you times that by 20 and I come up with a 20K ohm variable resistor needed. This will give you different voltages and allow you to come back to stock settings also.

OHM READING FROM CARD x 20 = VARIABLE OHM RESISTOR NEED

I ordered my variable resistors from Amazon. http://www.amazon.com/gp/product/B008IMQ73Q/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A3UJU66UCNEADW

Now that you got your parts needed its time to do some work. For the VR, pick the middle & one of the 2 outer legs to use & set it to the maximum 20k resistance before soldering it in. I use the outer leg right underneath the screw & cut the other off, that way I always set the VRs to turn the same way to increase/decrease resistance (& voltage) so it doesn't get confusing with multiple modded cards. Were going to use 1 lead & wire going to the mod point beside the ncp4206 controller & the other going to ground (right on the pci-e connector ground pin). The extra leg on the variable resistor you can cut off. Below is a pic of the ground used for the resistor.

I generally use a 2 wire molex type connector & glue that to the back near the VR. With wires coming off the card make sure they are fixed to the card well, they are pretty easy to pull on & don't want to rip the soldered connections. This is key make sure you secure the wires very well to the card as I have destroyed one card by not having it secured and wire got pulled on and ripped the point off the voltage controller and once that happens its pretty much a done deal. Hope you guys enjoy the mods if you have any questions please feel free to ask and I will help and possibly add it to the guide if I have forgotten anything. Will add more pics later once I drain my loop and remove my cards.

Solid Resistor Volt Mod Card running at 1.267 volts


Running the locked 1.21 volts best run
 

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cheers.. subbed for later!

Might give this a try, would be interested to know what clocks people can get at 1.3v and what temps (air, water, whatever)

Out of curiosity how did you work this out? Did you pull the datasheets for the IC's on the board or a combination of trial and error and previous experience?
 

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Discussion Starter · #3 ·
As far as knowing how to do it I never volt modded a card before. I got my soldering experience from modding xboxs not for illegal purposes but so I could play emulators and started doing it as a side business. The guide was compiled die to the great help of Ftw 420 and guides on hwbot. There is nothing I am aware of for the ti but it uses a similar pcb as the titan. The resistors table seen was from my own trial and error. I did have 4 780Ti but now I have 3 not from to much voltage but during the variable resistor mod a very small point was pulled before I secured the wire due to my little girl pulling on a hot soldering iron and I accidently pulled the wire with the point off. So on that note I am in no way a professional at this I just like to explore and push things and am willing to take the risk. So the risk is there of being out hundreds of dollars but the reward is there if you succeed. As far as the clocks increase I am not completely sure since I shut down due to to much power draw but that is because my seasonic is starting to go bad and I am trying to make it last till the 1500 w corsair psu comes out where I can push things.
 

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nice, yeah I've been soldering things for about 20 years and ruined my fair share of electronics!

Was just wondering about the history of the mod to try and determine if adding that resistor actually controls the set point of the VRM or if it is some secondary effect that just happens to give added voltage to the Vcore.

I assume 1/4W resistors should be adequate if it's just controlling the VRM?

Just a thought but you could make a pretty neat solution using a resistor ladder and dip switch which would give you slightly better repeatability in setting your voltage than a variable resistor. If you choose your value of R (maybe 470R given your list so far) I'm pretty sure you could cover most your range and the more resistors you switch in, the lower your resistance and the higher your voltage goes. Of course this would be non linear so using the same vale of resistor at each point may not be optimum but makes it simpler in that you don't have to worry about which dip position is enabled, just that there are 2 up and 6 down etc for your given voltage. And you can disable the mod by switching them all off


 

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Discussion Starter · #6 ·
Quote:
Originally Posted by skyn3t View Post

@doctakedooty great work man, I knew you know your things
thumb.gif
gonna add t his to the link in the 780 Ti OP. with your permission of course.
wink.gif
of course feel free to add a link. This weekend I will have it done friday when I get off I am going to break down my loop so I can take pictures for the guide.
 

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Discussion Starter · #8 ·
Quote:
Originally Posted by Jimhans1 View Post

I knew I should have put my "L" series glass on the camera. Sorry my pics didn't help out.
No they did I just realized I need more and where one of the mod points on the rear the first batchs are slightly different then yours soi needa pic of one of my first batch cards so i can show it on both.
 

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Quote:
Originally Posted by doctakedooty View Post

of course feel free to add a link. This weekend I will have it done friday when I get off I am going to break down my loop so I can take pictures for the guide.
You got it .
 

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Thanks for the update. Couple of questions, comments

- why use a 20k trimmer pot / rheostat on the front instead of, say, a 0.5k or 1k pot on the rear using the two points identified for the fixed resistor guide? Is it just so you can get a better mount for the variable resistor off the PCI-E socket?

- where you've marked '50k to ground' in yellow on one image is this referring to the range of your variable resistor or something else?

- I take it your variable resistor is soldered direct to the ground of the PCI-E socket and your white wire goes from the middle wiper position to the board?

- did I recall you saying that there were differences between some boards, was this just that one had a silk screen and the other solder on these solder points on the back?

- would be useful to know the exact make/model of the cards photographed for any subtle differences down the line.

- if doing a dip switch option like I suggested, it would require some thought to ensure that the wires to the switch are adequately strain relieved to avoid ripping the point off like what happened to you. I'd think at the very least I'd want to glue the wires to the PCB after soldering. Will have a think if I get round to doing this!

Thanks for the effort, guide looks good
 

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Discussion Starter · #12 ·
Quote:
Originally Posted by pharcycle View Post

Thanks for the update. Couple of questions, comments

- why use a 20k trimmer pot / rheostat on the front instead of, say, a 0.5k or 1k pot on the rear using the two points identified for the fixed resistor guide? Is it just so you can get a better mount for the variable resistor off the PCI-E socket?

- where you've marked '50k to ground' in yellow on one image is this referring to the range of your variable resistor or something else?

- I take it your variable resistor is soldered direct to the ground of the PCI-E socket and your white wire goes from the middle wiper position to the board?

- did I recall you saying that there were differences between some boards, was this just that one had a silk screen and the other solder on these solder points on the back?

- would be useful to know the exact make/model of the cards photographed for any subtle differences down the line.

- if doing a dip switch option like I suggested, it would require some thought to ensure that the wires to the switch are adequately strain relieved to avoid ripping the point off like what happened to you. I'd think at the very least I'd want to glue the wires to the PCB after soldering. Will have a think if I get round to doing this!

Thanks for the effort, guide looks good
-The trimmer pot on the front instead of the rear is because yiu could measure the resistance to find the correct trimmer ohm. Could you use ine on the back like you suggested I dont see why you couldnt. The solid ohm resistor was the trial and error while I waited in my order. I didnt go to far into it as I knew my vr would be here soon but just to play around with what the rear could do. I would say the rear would possibly be a good spot for the dip switch over the frint as the vr on the frint of the pcb allows almost any voltage you would like.

-the 50k ohm was from a titan pic via ftw 420. A 50k ohm would work but it would not allow tou to come back down to stock voltage so ignore that. I will edit the pic and have it removed.

-Thats correct silk screen and some had solder over the silk screen as far as I know are the only differences between them. Other then that the pcbs are the same to the best of my knowledge. I guess to deter people from modding or so they could identify it.

-the solid resistor mod was a ti pic but the vr mod was with titan pics the differences are nothing the cards should look the exact same as far as power delivery sections go. Differences between cards could be different resistances between the ncp controller for the correct vr needed. The card I used though were evga but I dint think the layout between brands should offer much variance.

-correct either way make sure to glue the wires or secure them so they do not easily pull off mine were pulled when my littke girl tried to grab my soldering gun and I quickly moved to keep her from burning herself and pulled the wire and point off.

No problem glad I could help anyone looking to try it. The information gathered for this mod was found by asking people here on ocn and info found elsewhere to do it. I am sure you guys with more knowledge can find better ways but hopefully this gives at least some insight into getting your foot in the door. I didnt know when I would get time to drain my loop to remove my cards so I used the pics I had to be able to finish the guide. I will clean some of it up as time permits and get pics of my cards up.
 

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Discussion Starter · #14 ·
Just to give a idea one of my cards max was 1316 core at 1.21 at the 1.287 shown on the multi meter I can do 1380 core some benchs 1400 core clock
 

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Good observation, did you not see the part where he posted he had reference cards or did you just not read the entire thread
 

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Discussion Starter · #18 ·
Quote:
Originally Posted by PhIlLy ChEeSe View Post

Your photos are not 780TI or titan cards as there is a six pin power connector in the photos............
There is a 6 pin titan and 780ti ref uses a 6 pin and a 8 pin. The ti photos are my personal cards.
 

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Quote:
Originally Posted by szeged View Post

Good observation, did you not see the part where he posted he had reference cards or did you just not read the entire thread
I was asking, and yes I read the thread can yo be more condescending to people! He was not clear in his statement I ask cause I want to do the Mod, Another question for the OP I saw in other Mods that there are things that need to be removed on the card to make the MOD work? Yours doesn't? IN the 780 owners thread, there linked to Kingpin cooling?
 

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Quote:
Originally Posted by PhIlLy ChEeSe StEaK View Post

I was asking, and yes I read the thread can yo be more condescending to people! He was not clear in his statement I ask cause I want to do the Mod, Another question for the OP I saw in other Mods that there are things that need to be removed on the card to make the MOD work? Yours doesn't? IN the 780 owners thread, there linked to Kingpin cooling?
sorry, you made it sound like he was trying to lie or something lol, sorry about that
biggrin.gif
i hope the mod works out for you if you do it.
 
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