8800GT voltage mods

[mud]

Here's a vGPU volt mod for the OEM version of the Galaxy 8800GT 512MB with non-reference 6-layer board and 3-phase power.


EDIT: If the VGPU jumper works on your card, then you probably don't need this mod. The jumper has 3 settings.
Looking at the front of the card with the monitor connectors to the left and jumper at the top, imagine these are the three jumper pins: "o o o"

o o o = ~1.12V
[o-o]o = ~1.22V
o[o-o] = ~1.32V



Now, on to the mod, if you want more than those three settings to play with.

First, the usual disclaimer: If the magic smoke comes out, it's not my fault. That said, this didn't hurt my card.



The red rectangle is our area of interest:



Zooming in:



I forgot to take a picture before I did the mod, so you can see how I did mine. I connected pin 4 of the DC-DC converter to ground through a 30K variable resistor (VR) in series with a switch. This allows me to disable the mod by simply flicking the switch.

You need to connect the red dot (Sorry, the actual point to solder is covered up by heat shrink tubing in the picture, but it's the left side of an SMD capacitor) to ground through a variable resistor. 30K ohms should be a good value, since the resistance to ground from that point is originally about 1.35K ohms. The teal spots are some handy ground points you can use. You can use whichever ground point you want, including ones I haven't marked in the picture.

The vGPU voltage will increase proportionally to how much the resistance between the red point and ground decreases. So if your stock voltage was 1.10V with an original resistance between the red point and ground of 1350 ohms, and you decrease the resistance to 1190 ohms by adding your VR and tuning it to 10.0K ohms, your new vGPU should be about 1.25V.

Here are some points to measure vGPU:




Some notes on my experience with the mod:
I saw vGPU increase by about 0.02V under load, so take that into consideration.
My stock vGPU was 1.23V, and since I'm just using stock cooling and I have a crap card anyway, the mod wasn't even worth doing. Hopefully it will help someone else though.
On my card, the vGPU jumper has no effect. Apparently if you have the retail version with HDMI connector, the vGPU jumper will increase voltage.

If anybody else tries it, report back!

[acer4ever]

In the retail [hdmi] version, the oc tool included shows an increase of 0.25v over the stock 1.2v for this card by just moving the jumper

http://72.14.203.104/translate_c?hl=...-225125-3.html




vcore 1.45v
vmem 2.02v
fan @ 1501rpm


There is a thread at [Hard]Forum just for this card,
and without a vmod some users are reaching higher oc results.

http://www.hardforum.com/showthread.php?t=1250946

[acer4ever]

EDIT:

some users are getting this card with Samsung 1.0ns instead of Qimonda

[mud]

Good to know. I have an OEM version from NCIX, and my particular card overclocks terribly at any voltage (1.22 - 1.50). It has 1.0ns Quimonda RAM. Also, the voltage jumper doesn't do anything from me.

[winbond]

Good to know. I have an OEM version from NCIX, and my particular card overclocks terribly at any voltage (1.22 - 1.50). It has 1.0ns Quimonda RAM. Also, the voltage jumper doesn't do anything from me.

that sucks, this card should be a OC monster, i hope other 3phase power cards overclock better,

[Boogerlad]

is there a vmem mod for the galaxy card? also, where do u measure the voltage of the vmem? lastly, those red points for the vgpu; do u put the positive wire from your ddm to the red point and the black wire from the ddm to ground or the red point beside it? sorry i'm acting like a noob, but 13 year olds just don't know that much about electrcity =P are there any problems with flashing the bios on this card because it's a non reference design? i wanna change the clocks and make it permanent, but i'm not sure if the rom chip is the same or not.

[largon]

Boogerlad,
Voltage = potential difference.
If you measure the potential difference between two vGPU measuring points your result will be 0 (or very close to it). The difference between vGPU measuring point and ground is what you're interested in.

[Boogerlad]

oh, thanks man! xs is great cause everyone is so willing to help.

[andrew2004gto]

Ok PLZ someone help anyway i have 580 power supply and a 585 power supply anway i had problems with the 585 cuz my wireless mouse wouldnt work weird ya,and i tried the volt mod nothing and so i just left in contact but i switched to the 580 and than all of sudden i could go from 730/1782 to 756/1836 stable but i tried turnin the screw to get more volts nothing happens but i find the spot where it goes back to normal volts, so anyway is my 580 watt power supply holding my back, my system specs e4300@3550 1.52 volts, 2x4gb at 1052 at 2.3 volts, 2 harddrives, wireless keyboard, wireless mouse, wireless card, 1 dvd buring and about 6 fans so u think my power supply holding me back o yea 26watt on the rail

[Deux]

My OEM Galaxy card clocks like crap too. 712 Core 1625 Shader mem 1050 havent measured stock voltage yet.

Edit: Just measured and HOLY CRAP 1.31 IDLE. Isn't that really high for stock? Can I RMA based on this?

[Astennu]

I Did the V-mod and mounted a VF900 cooler.

With VF900 and stock 1.15v i could do 700-1830-1900 @51c GPU temp

Now i modded to 1.25v and testing 775-2000-1900 @ 57c GPU temp.

It seems to work fine 800 gpu gives instant freez in 3dmark 06 and 2050 shader freezes in game 2.

Tomorrow i will try 1.3vto bad my gpu clock wont go that high but i'n running air cooled so i have to be careful with the temps.

And BTW ATi tool is not stressing all the parts in the chip enough. I could run ATi tool @ 700-1730-1900 @ stock cooling for more then 30 min. And still got crashes in games like supreme commander and Trackmania United. It was my GPU clock.

Same with the 800-2000-1900 setting it ran fine in ATi tool average 610 fps but instant crash in 3dmark. Something is holding the card back and not stressing all the components.

[acer4ever]

Good to know. I have an OEM version from NCIX, and my particular card overclocks terribly at any voltage (1.22 - 1.50). It has 1.0ns Quimonda RAM. Also, the voltage jumper doesn't do anything from me.

Strange,
moving the jumper allows to increase core up to 750,
even at stock clocks moving the jumper increases core temp 5ºC

I assume it is working.

[natedog420]

i did the removal of the 2 smd or whatever there called and no more shutdown woohoo!!!. im at 1.38 idle and 1.46 load witch is good foe me cuz its low idle volts. im call of duty 4 and atitool stable for 24/7 operation. heres a screen shot of what i did real quick. let me know wjhat you think of my card. i dont know if i would call it a monster but who knows. i have tried and higher volts. can do 900 core but get few artifacts in atitool. might try higher volts but for now i will let this voltage settle in while i get more brave with voltage. temps dont break 58c or so depending on ambient temps. and is it ok to bench for periods of time say hour or 2 with memory over 1000mhz? i dont wanna hurt my card just ran it at 951 always no higher cuz of what people said

[Astennu]

I did some testing with the Ozone Fun benshmark and that one is realy stressing the shaders of the card. The temps are 90c @ 1.266v @ 775-1836-1900. Its clear ATi tool aint stressing it because my temps with the ATi stress where 70c on those settings.

I also found out that the ozone test did not stress the core that much but it did stress the shaders to the max. When i launch ATi Tool on those 90c temps it crashes on my core clock of 775 when the temps go down it can manage to run a longer period.

So its hard to 100% stress test these cards for 24/7 usage.

[XSS]

Work this mod at a 8800GT with no Reference Design ?

I have the Gainward 8800GT GLH 512MB

[Astennu]

I noticed a interesting thing. In under ATi Tool load i measured 1.225v with Ozone Furbenshmark load i measured 1.25v. It seems that the card will give the card more juice depending on its load ? Fur bensh also gives 20c higher temp then ATi tool. ATi tool is still 10-15c higher than most games.

[Boogerlad]

it won't work with it. however, if you post some pics, some people will be able to help you. i can't though, sorry

[mud]

is there a vmem mod for the galaxy card? also, where do u measure the voltage of the vmem? lastly, those red points for the vgpu; do u put the positive wire from your ddm to the red point and the black wire from the ddm to ground or the red point beside it? sorry i'm acting like a noob, but 13 year olds just don't know that much about electrcity =P are there any problems with flashing the bios on this card because it's a non reference design? i wanna change the clocks and make it permanent, but i'm not sure if the rom chip is the same or not.

There is a vmem mod, I actually did it by accident before I did the vgpu mod. It is easier to do, but I doubt it would help you at all unless you have some good cooling on your memory chips. Increasing my memory voltage decreased my max memory clocks. If you're really interested I could make a guide.

Your memory voltage can be measured on many of the caps behind the memory chips. It will be about 2.0V. Don't be afraid to poke around on there with your DMM (just don't short out anything with your probe, and make sure you're measuring voltage, not current!)

Flashing a modified version of the Galaxy BIOS is not a problem. You can use nvflash 5.57 and NiBiTor just like normal. However, I suspect that a BIOS from a reference board 8800GT might not work.

As another thought, I'm still not completely sure that the VGPU mod guide I made is correct. I measure about 1.13V on a bunch of caps on the back of the board behind the GPU, which is not the same voltage as I measure on the big caps (marked with red dots on the picture).

[mud]

Work this mod at a 8800GT with no Reference Design ?

I have the Gainward 8800GT GLH 512MB

Like boogerlad said, post some pictures (closeups of front and back of card) and someone can probably help you. The only two board layouts I know of are the reference design and the one used by Galaxy (and maybe others?). If yours isn't the reference design, perhaps it is the same as the Galaxy design. Look at the pictures I posted above and see if you can tell.

[mud]

GALAXY 8800GT 512MB VGPU JUMPER

I think I figured the voltage jumper out. I just got another Galaxy 8800GT, and this one has the rectangular dual-slot cooler. The jumper on this card works as follows:

Looking at the front of the card with the monitor connectors to the left and jumper at the top, imagine these are the three jumper pins: "o o o", and this is the jumper: "[ - ]"

o o o = ~1.12V
[o-o]o = ~1.22V
o[o-o] = ~1.32V

That should pretty much take care of the need for a voltmod for this card for most people.

My new card overclocks much better than the one I have with the round heatpipe cooler. My round cooler had an uneven base, so it didn't work very well. The best I could do was about 675/1674/900 at 1.22V, and up to ~85 C loaded in atitool. The new one is doing 750/1836/1100 so far at 1.32V, and only 75 C loaded. It is a lot louder though, similar to the newer 8800GT stock cooler at ~80%, and the fan speed of it doesn't seem to be adjustable. I couldn't even hear the round cooler over my other fans at 100%.

[Luka_Aveiro]

GALAXY 8800GT 512MB VGPU JUMPER

I think I figured the voltage jumper out. I just got another Galaxy 8800GT, and this one has the rectangular dual-slot cooler. The jumper on this card works as follows: (...)

Does the reference design 8800GT jumper have something to do with any vGPU increasing???

[Droperidolum]

Could you help me find Vmod for non reference Palit 8800GT?
Some pics on Russian forum:
http://forums.overclockers.ru/viewto...599844#4599844
There are RT8802A on GPU. I can measure resistance if needed.
Thank you!

[XSS]

Here are some pics !

[XSS]

More pics http://hbfreak93.hb.funpic.de/Graka/

[Droperidolum]

Arrrhhh!!! It`a the same as my palit!
RED PCB!!! Such a shame for GeForce to be a red...
no, this Vmod don`t work on not-reference,
but we must to find OUR mod!!!