7800GTX overclocks with Volt Mods??

[madgravity34]

there is a vddq mod? Is that the same as the vdd mod? (Dont know what the q stands for). Can we get a linky? It may not work, but hell, at least some of us could try to see if it helps.

[VParis85]

Hey just did my volt mods today and cant seem to get it to work. I cant adjust the VGPU says 1.366 @ 2d and 1.59 @ 3d I used this guide http://www.malvescorner.net/7800.html for my 7800gtx 256 I set my DMM to 2V and i dont get a reading for the mem at all if i set it to 20v on the DMM i get .001 i solderd the ground of the trimmers to the main power grounds comming on to the card from the PSU some one help me!!!!!

[ViperJohn]

Hey just did my volt mods today and cant seem to get it to work. I cant adjust the VGPU says 1.366 @ 2d and 1.59 @ 3d I used this guide http://www.malvescorner.net/7800.html for my 7800gtx 256 I set my DMM to 2V and i dont get a reading for the mem at all if i set it to 20v on the DMM i get .001 i solderd the ground of the trimmers to the main power grounds comming on to the card from the PSU some one help me!!!!!

The Vcore is working as those voltages are well above stock. The reason you can't adjust it is you used leg 1 and 3 on the trimmer instead of 2 and 3.

Viper

[VParis85]

Hello John I used legs 1 + 2 for both mods I sent you a picture to you email adress also i cant measure my memory voltage at point c610 Take a look at the pic anf let me know what i have to do thankyou

[ViperJohn]

Hello John I used legs 1 + 2 for both mods I sent you a picture to you email adress also i cant measure my memory voltage at point c610 Take a look at the pic anf let me know what i have to do thankyou

If you used legs #1 and #2 the modded voltage would go down as you turned the screw clockwise. You have just turned the adjust screw fully clockwise (max pot resistance) and are at minimum mod voltage lol.

Viper

[VParis85]

Yes john I understand I have to turn the screw clock wise to lower the ohms therefor increasing the voltage but it dose not seem to be working maybe i damaged the pots whille heating up the shrink wrap i have two mor of each.
Also i cant seem to measure the memory voltage hear at C610 my DMM has 2, 20, 200, 1000 for DVC 2V pins out when i try to measur it ans 20 gives me .001

[VParis85]

AWWWWWW man thouhtt I fried it, I broke off the solder from point 569 so i resoldered it put it back in PC..... no picture so i broke off the solder agian and reapply it and plug it back in start up no picture......... Stupid me forgot to plug in the monitor cable though all the comotion LOL any way im gonna save the project for another day........Probly tommarow John my mem Vmod is hooked up right but my voltage meter must suck because even with out the VGPU vmod on the board it still measures 1.366 2d and 1.59 3d which i know are not right. So my project is on hold till i get a better Voltage meter ill post back up upon more work and completion with my overclock thanks for your help so far John

[VParis85]

Every thing is done totoday curently running Vgpu at 1.65 and Vdd at 2.3 now i need to know what bios and drivers to use to go past OCP cuz when i clock over 590 the card stays at 2d mode so some one help me out please thankyou

[pumbertot]

Every thing is done totoday curently running Vgpu at 1.65 and Vdd at 2.3 now i need to know what bios and drivers to use to go past OCP cuz when i clock over 590 the card stays at 2d mode so some one help me out please thankyou

use nibitor, mod your bios and change active performance level to ensure it goes 3d

[Revivalist]

Hey guys, I just v-modded my 7800GTXs, put pelt blocks on them and installed them. . . . They're certainly not professional Viper John quality, but it was fun doing it myself. . . . Here's some pics.

The top




The bottom


Edge on (with my lovely wife assisting me with her hands. )


Here they are installed . . .







But there's some bad news . . . . I just discovered that the GPU and memory on the upper card aren't getting any voltage. I tested the pints right above the PCI-E power connector and it's getting 12V. But I felt the voltage regulator heatsink and it wasn't hot like the other card that's working. I know this card was working before because I tested it right after doing the v-mod. So this problem occured somewhere between the time I installed the TEC-block and installing it in the case. . . .

Is it possible that the card is just getting grounded somehow and needs to be adjusted, or would that mean the card is dead? . . . I'm really not sure what exactly to try at this point. I really hope I don't have to take my whole rig apart again for nothing.

[DangeR!]

Hi,
thnx for this thread, I sucesfully vmodded my g/c today and wanted to thank you all for your input into this thread. It made the job alot easyer having all this info to hand in one spot.

I did it like viperJohn did, soldering the trimmers directly, instead of using wires. I did use some wires for linking a h/d molex to each voltage read point for mem/core and one for grnd. This, to me, makes the reading of the voltage ALOT easyer as you can rest the tester leads in the molex while changing modes (2d 3d).

When I get a digital camera I will show off my mod. It looks no where neare as neat as viperJohns, but not bad for a new commer to vMods. i.e. there are big blobs of solder where as *Johns are bearly visable lol.

My voltage is at 1.528 and I am able to pass the test in coolbits for 550MHz, I get artifacts though... need more voltage hehe.

just out of interest. I'm water cooled (maze4 and OCZ ramsyncs) and was wondering what voltage should I be ok in going up to, for both mem/core.

thnx again peeps and happy modding.

[son_of_liberty]

hi all
noobisch question

isnt this mod possible with a pencil?
http://www.xtremesystems.org/forums/...6&postcount=47

[Revivalist]

hi all
noobisch question

isnt this mod possible with a pencil?
http://www.xtremesystems.org/forums/...6&postcount=47

Yes, but I don't think it's as controlled or that you can reach as high of voltages.

[ViperJohn]

hi all
noobisch question

isnt this mod possible with a pencil?
http://www.xtremesystems.org/forums/...6&postcount=47

No it is not. There is no low side voltage divider resistor to pencil. The voltage divider is created when and by the trim pot that is added.

Viper

[EmoAddict15]

I have an XFX 7800 GTX 512MB Edition which is the same mod (just a little bit different spots I'm looking for) according to this guide: http://www.vr-zone.com/?i=2943

or at least it looks that way for the VDDR mod, anyways. I just took the heatsink off did took a 50 then 150 grit and steel wool to it and slapped some AS5 on it. I'm more interested in pushing the VDDR but VCore is welcome to, right now i get 575/1800 after that I get funny artifacts in Oblivion (amazingly I can get to like 1875 in Quake 4 and other engines before it starts getting funny). Will increasing the VDDR give me a huge boost or not really on stock? I do have a swiftech waterblock meant for the NV40 which I never used I could probably use that (the dies are the same size and so are the mounting holes right?) Anyways, thanks in advance.

[mikenam]

yesterday i did the mod. when i installed nothing booted. when i removed my computer booted but when it gets to windows it freezes. ima bout to reinstall the mod again hopefully doing that will save my card.


thanks

[Mat347]

I just comleted the Vcore mod last night, Thanks for the great pics ViperJohn, those are the best I've seen and don't think I could have done it without them
There were a few points where I thought I had lost my card due to the suprisingly small soldering that was required. I needed a finer tip on my iron as well as a tiny soldering wick...but it all came up fine...thank goodness!
With my watercooled 256 I'm stable(no artifacts in ATITool) at 605/1460 with system load temps of ~52C on the GPU. The voltage required is a little high at 1.7. I got up to 630 but was at 1.8 and I need 24/7 settings so I backed it down. But I'm content with my solid 10k 3d05 score.

But my main concern is the fact that it will stay at 1.7 while in windows. I have flashed the BIOS before the hard mod in hopes of doing a soft Vmod. I tried several different settings on everything, with no luck obviously. But I have flashed the factory BFG BIOS back into the card several times with the factory voltages of 1.2/1.4/1.4. I tried changing the middle voltage(thrtl I think??) to 1.2 which worked in keeping the windows voltage down, but it also kept the 3d voltage from going up. As of right now I have the factory BFG BIOS loaded and during POST I get the low voltage, but as soon as XP starts to load it jumps up. This leads me to believe there may be a simple software setting I can change....is this true?? Any insight would be greatly appreciated!

ViperJohn, I saw the 650MHz clock in your sig and was hoping I'd get there, but am content with the 605, what are you using to get that clock though? Is it just a freak of nature core?? Mine is one of the first batches BTW, I got it right when it came out when Dell had them for $500.

[ViperJohn]

I just comleted the Vcore mod last night, Thanks for the great pics ViperJohn, those are the best I've seen and don't think I could have done it without them
There were a few points where I thought I had lost my card due to the suprisingly small soldering that was required. I needed a finer tip on my iron as well as a tiny soldering wick...but it all came up fine...thank goodness!
With my watercooled 256 I'm stable(no artifacts in ATITool) at 605/1460 with system load temps of ~52C on the GPU. The voltage required is a little high at 1.7. I got up to 630 but was at 1.8 and I need 24/7 settings so I backed it down. But I'm content with my solid 10k 3d05 score.

But my main concern is the fact that it will stay at 1.7 while in windows. I have flashed the BIOS before the hard mod in hopes of doing a soft Vmod. I tried several different settings on everything, with no luck obviously. But I have flashed the factory BFG BIOS back into the card several times with the factory voltages of 1.2/1.4/1.4. I tried changing the middle voltage(thrtl I think??) to 1.2 which worked in keeping the windows voltage down, but it also kept the 3d voltage from going up. As of right now I have the factory BFG BIOS loaded and during POST I get the low voltage, but as soon as XP starts to load it jumps up. This leads me to believe there may be a simple software setting I can change....is this true?? Any insight would be greatly appreciated!

ViperJohn, I saw the 650MHz clock in your sig and was hoping I'd get there, but am content with the 605, what are you using to get that clock though? Is it just a freak of nature core?? Mine is one of the first batches BTW, I got it right when it came out when Dell had them for $500.

Well it sounds like you are running a 3D desktop. Try changing to the Windows Classic Desktop and see if that changes the behavior.

Viper

[Mat347]

Well it sounds like you are running a 3D desktop. Try changing to the Windows Classic Desktop and see if that changes the behavior.

Viper

I was running the plain XP desktop, swapping to classic didn't change the voltage. Thanks for the suggestion though. I guess if it blows, it blows
I just hope G80 is out by then as I was planning on upgrading to it anyway.

[VParis85]

Hello All, i volt moded my xfx 7800 gtx a while back, and took a 4 pin mollex connector and solder 2 pins to the voltage check points which works awsome.
anyways in a need for more speed i turned up the voltage to 1.75 gpu and 2.4 mem 24/7 am running 650 mhz gpu and 1525 mhz on th mem. im on water mx load temps are 36* will it last?

[ViperJohn]

Hello All, i volt moded my xfx 7800 gtx a while back, and took a 4 pin mollex connector and solder 2 pins to the voltage check points which works awsome.
anyways in a need for more speed i turned up the voltage to 1.75 gpu and 2.4 mem 24/7 am running 650 mhz gpu and 1525 mhz on th mem. im on water mx load temps are 36* will it last?

Is that a 256 or 512 MB card??? My bet is it's a 256 card as most 512's would have shutdown
on Vcore over voltage well before you got to 1.75 Vcore.

You are probably losing memory OC with 2.40 Vmem especially if the card is a 256 MB where
the Vdd and Vddq are tied together off the same on card power supply.

Viper

[VParis85]

Yes it is 256
Humm thats interesting i will have to see what the sweet spot is for the mem voltage
what kind of voltage got you to the 1600 range viper as bumping up the memory i have seen great increase in FPS

[ViperJohn]

Yes it is 256
Humm thats interesting i will have to see what the sweet spot is for the mem voltage
what kind of voltage got you to the 1600 range viper as bumping up the memory i have seen great increase in FPS

Every card is different. I found 2.250-2.350 was the typical range for 256MB cards. Note to that almost all of the cards I mod have tightened memory timing...sometimes seriously tighten if the particular card will do it.

The 1620mem 256Mb card was just a fluke of nature (or manufacturing). Truth be told getting 256Mb card over 1500 memory perfectly clean in everything was hard. If you know where and when and what to look for in certain tests it wasn't hard to see the memory go dirty even though it would run all other tests cleaner than a whistle far faster. There are a couple of places in 3DM03's Battle of ProxyCon that can just clobber a 7800's max clean in everything memory OC.

Viper

[LittleDevil]

Can anyone post cleaner picture of vdd mod?

regards

[AC/DC]

Hello everybody.

What's the max voltage for GPU on 256 version ?

Thanks.