[7900/7950 GT Voltmod Guide] -
7900/7950 GT Voltmod Guide
Discuss 7900/7950 GT Voltmod Guide
Posted by: Apokalipse
[size=5]7900/7950 GT Voltmod Guide[/size]
Voltmodding a 7900/7950 GT can be done to increase the overclock you can achieve. If your 7900/7950 GT has a reference PCB, this mod can be done. There are a few 7900/7950 GT’s that don’t use the reference PCB (I think this includes most of the 512MB versions, I could be wrong)
[size=4][b]Disclaimer:[/b][/size] Nobody on Tech-Forums.net are responsible if you kill your card. Do this at your own risk.
I recommend that you read this guide carefully, and understand what you are doing before going ahead.
the biggest risk is soldering resistors. If you decide to do the resistor mods, be really careful. If you are not comfortable with soldering, I do not recommend you attempt the resistor mods.
The conductive pen mod is not very risky; however I still advise you be careful.
If you only have stock cooling, I recommend a maximum of about 1.4V
Make sure you have drawn the right traces, and they are not touching any other contacts.
[size=4][b]What you need to voltmod:[/b][/size]
[list][*]Conductive Pen (highly recommended)
[*]Soldering Iron (optional, to increase voltage past 1.55V)
[*]Solder – preferably very thin (to be used with soldering iron)
[*]Resistors (optional)
[*]Pencil[/list]
[IMG]http://img.photobucket.com/albums/v133/apokalipse/whole_card.jpg[/IMG]
The areas in the red boxes are the areas you need to look for when voltmodding your card
[size=4][b]Conductive Pen mod:[/b][/size]
[IMG]http://img.photobucket.com/albums/v133/apokalipse/conductivepen.jpg[/IMG]
The above picture shows three possible sets of routes you can use to increase voltage (in the pink boxes)
I recommend using the lower set, because it is the easiest to do. But remember to only use one set.
[IMG]http://img.photobucket.com/albums/v133/apokalipse/4thoption.jpg[/IMG]
This is another set you can use. I'd recommend it after the set in the bottom pink box.
[color=green]Green[/color] trace: gives +0.05V increase
[color=blue]Blue[/color] trace: gives 0.10V increase
[color=red]Red[/color] trace: gives +0.20V increase
You can combine the colours to make different voltages:
[b]7900 GT[/b]
1.2V = none (stock)
1.25V = [color=green]green[/color]
1.3V = [color=blue]blue[/color]
1.35V = [color=blue]blue[/color] + [color=green]green[/color]
1.4V = [color=red]red[/color]
1.45V = [color=red]red[/color] + [color=green]green[/color]
1.5V = [color=red]red[/color] + [color=blue]blue[/color]
1.55V = [color=red]red[/color] + [color=green]green[/color] + [color=blue]blue[/color]
[b]7950 GT[/b]
1.4V = none (stock)
1.45V = [color=green]green[/color]
1.5V = [color=blue]blue[/color]
1.55V = [color=blue]blue[/color] + [color=green]green[/color]
1.6V = [color=red]red[/color]
1.65V = [color=red]red[/color] + [color=green]green[/color]
1.7V = [color=red]red[/color] + [color=blue]blue[/color]
1.75V = [color=red]red[/color] + [color=green]green[/color] + [color=blue]blue[/color]
[size=4][b]Resistor Mod:[/b][/size]
[size=1]Note: I recommend you use the same style of resistors used on the card in the first place, like I’ve done. They are kinda hard to find, but worth it.
If you cannot find that style of resistor, you can do what I did and steal resistors from old parts you don’t use anymore (Preferably dead. I have several dead Pentium 3 motherboards which I took the resistors from)
Another side note, that style of resistors is very easy to lose. So be careful.[/size]
To increase voltage over 1.55V (1.75V for 7950's - though I don't recommend that), you need 1 x 50Kohm resistor (47Kohm will be fine)
[IMG]http://img.photobucket.com/albums/v133/apokalipse/resistor.jpg[/IMG]
[size=1]In this picture, the highlighted resistors you see are not the ones that came with my card. I’ve already replaced them, but I don’t feel like swapping them back just for the picture[/size]
When you get your card, The red resistor measures 5Kohm. By replacing this with a 50Kohm resistor, you increase the voltage by +0.3V (I used a 47Kohm resistor, which I calculated to give a +0.28V increase)
Replacing this resistor alone increases the voltage from 1.2V to 1.5V (or if you use a 47Kohm resistor, 1.48V)
Do this in conjunction with a conductive pen mod to increase the voltage further.
[b]7900 GT[/b]
1.5V = [color=red]resistor[/color]
1.55V = [color=red]resistor[/color] + [color=green]green[/color]
1.6V = [color=red]resistor[/color] + [color=blue]blue[/color]
1.65V = [color=red]resistor[/color] + [color=blue]blue[/color] + [color=green]green[/color]
1.7V = [color=red]resistor[/color] + [color=red]red[/color]
1.75V = [color=red]resistor[/color] + [color=red]red[/color] + [color=green]green[/color]
1.8V = [color=red]resistor[/color] + [color=red]red[/color] + [color=blue]blue[/color]
1.85V = [color=red]resistor[/color] + [color=red]red[/color] + [color=green]green[/color] + [color=blue]blue[/color]
[b]7950 GT[/b]
1.7V = [color=red]resistor[/color]
1.75V = [color=red]resistor[/color] + [color=green]green[/color]
1.8V = [color=red]resistor[/color] + [color=blue]blue[/color]
1.85V = [color=red]resistor[/color] + [color=blue]blue[/color] + [color=green]green[/color]
1.9V = [color=red]resistor[/color] + [color=red]red[/color]
1.95V = [color=red]resistor[/color] + [color=red]red[/color] + [color=green]green[/color]
2.0V = [color=red]resistor[/color] + [color=red]red[/color] + [color=blue]blue[/color]
2.05V = [color=red]resistor[/color] + [color=red]red[/color] + [color=green]green[/color] + [color=blue]blue[/color]
I do not recommend going further than about 1.7V. This is [i]with[/i] aftermarket cooling.
so for 7950 GT's, I would recommend choosing [i]either[/i] the resistor mod, [i]or[/i] the conductive pen mod
these cards can get quite hot if you put the voltage high.
In the picture above, the green resistor controls the switching frequency. It measures 86Kohm
By reducing the resistance to 46Kohm, you will increase the switching frequency, and hence the overclockability of your card.
This can be done by doing one of the following:
[list][*]drawing over it with pencil, and measuring the resistance using a multimeter (if you are not comfortable with soldering, you may want to try this)
[*] soldering a 100Kohm resistor in parallel with it
[*]replacing the resistor entirely with a 45-47Kohm resistor[/list]
Note: this resistor can even be taken down to about 30Kohm if your overclocks are not going as high as you’d like
[size=4][b]Heatsinking IC’s:[/size][/b]
If voltmodding your video card, it is recommended that you use aftermarket cooling for your GPU. Also some of the IC’s will run hotter with a voltmod.
These 3 IC’s in particular can get hot if you go above about 1.55V
[IMG]http://img.photobucket.com/albums/v133/apokalipse/ICs.jpg[/IMG]
[IMG]http://img.photobucket.com/albums/v133/apokalipse/ICs_sinked.jpg[/IMG]
If you go to 1.65V and above, the capacitors at the back of the card can also get hot. You might want to sink them too:
[IMG]http://img.photobucket.com/albums/v133/apokalipse/capacitors_sinked.jpg[/IMG]
[color=green]I haven't made a memory voltmod section. at least not yet.
though if anybody else wants to make one and post it here, you're more than welcome to do so[/color]
Posted by: Yoad
Very nice guide!
Also if you didnt add it [I didnt read it thoroughly], I suggest using masking-tape for drawing the conductive ink, so the lines will be nice and smooth.... conductive pen ink flow tends to mess up straight lines no matter how hard you try ;) .
Also, would be awsome if you make another part of the guide showing HOW to solder new resistors ;) not many knows how, me in detial, haha.
-Jo.
Posted by: harley3344
yes im 16 and havnt had the chance to soder much ( I will practice on a radio or a toy car first , lol) it would help if u did thanks
Posted by: KingAustin
So, how did you figure this out exactly?
Posted by: Apokalipse
the knowledge would have originally come from Nvidia employees I'd say. I got the info by reading a lot of stuff, using google.
I'd say xtremesystems and anandtech are worth mentioning, but I did look at a fair few sites.
what I did was collect all the necesary information, and put it all together in this guide.
something I did create was a possible formula for the 50Kohm resistor mod (I'm not sure exactly how accurate it is, because I haven't tested it):
V = kR + C (voltage = V, resistance = R, in Kohm)
1.2 = 5k + c (1)
1.5 = 50k + c (2)
(2) - (1)
0.3 = 45k
k = 0.3/45 = 1/150
1.5 = 50/150 + C
C = 1.5 - 1/3 = 7/6
[b]V = R/150 + 7/6[/b]
or:
[b]150(V - 7/6) = R[/b]
where V is the desired voltage, and R is the resistance in Kohms required to get this voltage.
again, I'm not sure how accurate it is, so I didn't include it in the actual guide. but that's what I used to calculate that I got 1.48V using the 47Kohm resistor.
one other thing, I haven't seen anyone else sink their capacitors. that was my idea.
Posted by: Yoad
as long as its your card in the pictures, and you're the one shooting the pictures, you legaly don't own anyone any sort of credit.
what about the rest of the stuff I asked about? ^_^;
-Jo.
Posted by: Apokalipse
I might make a soldering guide if I have time, but it's something I don't always have right now, this being my final year of school and all.
Posted by: Yoad
ahh.
same here lol..
Well thanks anyway ;) this guide is pretty nice as it is :D .
I wonder if X1900XT's has any physicall mods..
-Jo.
Posted by: Apokalipse
not that I know of.
the ability to voltmod was part of the reason I got my 7900 GT though. that, and it cost a fair bit less than a GTX or any X1900.
I've made it faster than a GTX anyway.
Posted by: Lord AnthraX
:(
Thanks...freind :(
Posted by: LaserCobra
That card must weigh 15 pounds (6.82Kgs) with all those ram sinks and gpu sink =)
Not to discredit your effort but there's another forum that has slightly better depiction of the modification as well as how to vmod the mem. I'd be happy to point anyone interested to that URL.
Posted by: Apokalipse
it's not that heavy. a bit heavier than most cooling solutions, but doesn't strain the card.
as a matter of fact the VF900 is pretty light.
of course there's going to be better guides out there. I still think it's easy enough to follow.
the only real prerequisite for part of this guide, is to know how to solder.
Posted by: Sevoma
It's a very nice guide although the pictures are very blurry. It is kind of hard to see where you have to solder. Mabey you can get clearer pictures in macro mode (most cameras have it).
Posted by: Apokalipse
yeah, I took several pictures. the ones I put there were the ones that came out best. I think the close range has something to do with it.
what kind of picture is normally associated with macro mode?
Posted by: Snake-Eyes
Macro mode = object is about 3 inches [7.6 cm] (100% literally) away from camera lens.
Posted by: Apokalipse
there's several settings on the camera, but I am not sure what would be "macro mode"
Posted by: BennyV04988
Is this thing worth it? I mean, with my card im running the old drivers so the fan isnt on full blast, OC'd to 540 / 780 and w/o the fan on full i still only hit like 60C. I might throw in a 120mm fan and do this voltmod. What kind of performance increase can you get in practical gaming? at say...650 core?
Posted by: Apokalipse
650 core will usually give you over 33% extra performance; provided your CPU doesn't bottleneck it.
currently I have a Sempron 2800+ at 2.0GHZ. this has been bottlenecking it a fair bit. (that's the next thing for me to upgrade - but I'm still waiting on my tax return)
but, if you turn the image quality up to full, then the card will use more of its potential, even with a slower CPU.
Posted by: ynnubekacnap
I own a XFX 7900GT volt modded with a vf900 fan i idle around 59-60c not sure if its normal im just curious to know if it is
Posted by: Apokalipse
as long as it doesnt go past about 70
what are your load temps?
(you can use ATI Tool artifact scanning, then look at the temperatures)
Posted by: ynnubekacnap
well under full load i would say tops 70-72c OC'ed settings at 635/835
edit
wow while i was using the ATI tool scan i checked the nvidia core temp and read as high as 110! :(
Posted by: Apokalipse
yeah, something's not right there
either your temperature monitor is wrong, or your heatsink isn't making that great contact
have you got arctic silver 5?
Posted by: Lord AnthraX
[QUOTE][i]Originally posted by apokalipse [/i]
[B]as long as it doesnt go past about 70
what are your load temps?
(you can use ATI Tool artifact scanning, then look at the temperatures) [/B][/QUOTE]
You shouldn't start worrying until you hit 90....
Posted by: ynnubekacnap
sorry give me 1-3 days ill get back to you on this
Posted by: Apokalipse
[QUOTE][i]Originally posted by Lord AnthraX [/i]
[B]You shouldn't start worrying until you hit 90.... [/B][/QUOTE]it's better to give it some headroom though
Posted by: ynnubekacnap
i figured the problem out, awhile ago i did a half *** job applying a5 to the gpu core, well i redid it and now im running temps as low as 40c : )
Posted by: vipercrazed
lol 110c why even use a heatsink? ha ha ha
that is a insane difference man,
my 7900gt is watercooled i really want to try this but the gpu block is really really bad and im waiting till i get a swiftech mc60 or w/e its called.
Posted by: Apokalipse
what are your temps right now?
Posted by: Pepsiboy700
As far as I know this volt mod works on my EVGA 7900 GS. I set the core to 1.55v and got an oc from 450 to 690. When I get better cooling will aim higher!
Posted by: Apokalipse
I also read that these voltmods work on the 7950 GT's
Posted by: Apokalipse
I just found out my voltmod guide is the first hit on a google search:
[url]http://www.google.com.au/search?num=100&hl=en&safe=off&q=%227900+gt%22+voltmod+guide&btnG=Search&meta=[/url]
*edit*
I can confirm that this definitely does work on 256MB 7950 GT's.
I put my 7900 GT into a friends computer (he has an X2 3800+ at 2.4GHZ) and it shorted out - I am pretty sure it was his power supply that did it.
So I went and got a Leadtek 256MB 7950 GT (AU$355, which is a great price), and used my conductive pen to add 0.2V to it (stock voltage is 1.3V in 2D, 1.4V in 3D).
at the current voltage it works at 710MHZ. I'll try upping the voltage later to try and get past 750 again.
Posted by: vernong1992
well i wanna volt mod my current video card, but its not for my Video card
Posted by: Apokalipse
I think 7600's can be voltmodded. I'm not sure about yours, since it is a 512MB version.
Posted by: nitestick
pretty much any card can be volt modded, it's a matter of finding a guide or having enough knowhow and specs to be able to make your own mod. it will be hard to find a mod for that 7600GT because it must be a non-reference card if it has 512mb of memory.
Posted by: Apokalipse
[QUOTE][i]Originally posted by Marketing87 [/i][QUOTE][i]Originally posted by KingAustin [/i]
[B]So, how did you figure this out exactly? [/B][/QUOTE][/quote]
[QUOTE][i]Originally posted by Apokalipse [/i]
[B]the knowledge would have originally come from Nvidia employees I'd say. I got the info by reading a lot of stuff, using google.
I'd say xtremesystems and anandtech are worth mentioning, but I did look at a fair few sites.
what I did was collect all the necesary information, and put it all together in this guide.
something I did create was a possible formula for the 50Kohm resistor mod (I'm not sure exactly how accurate it is, because I haven't tested it):
V = kR + C (voltage = V, resistance = R, in Kohm)
1.2 = 5k + c (1)
1.5 = 50k + c (2)
(2) - (1)
0.3 = 45k
k = 0.3/45 = 1/150
1.5 = 50/150 + C
C = 1.5 - 1/3 = 7/6
[b]V = R/150 + 7/6[/b]
or:
[b]150(V - 7/6) = R[/b]
where V is the desired voltage, and R is the resistance in Kohms required to get this voltage.
again, I'm not sure how accurate it is, so I didn't include it in the actual guide. but that's what I used to calculate that I got 1.48V using the 47Kohm resistor.
one other thing, I haven't seen anyone else sink their capacitors. that was my idea. [/B][/QUOTE]