7800gs volt mods

[imperiousleader]

Thanks to some excellent info on Guru3d forums and VRzone these cards can in most cases I guess be overclocked quite
a lot higher when V modded

Vgpu mods http://forums.guru3d.com/showthread.php?t=200420

Vmem mods http://vr-zone.com/index.php?i=3317

First I Vmem modded my MSI 7800gs G70 which so far has gotten my card stable at 1621mhz, probably some more to come.
Then I performed the Vid2 to ground mod from guru3d forums which when running in 3d mode has upped the voltage on
the Gpu from 1.4v to 1.5v.
Anyone who has overclocked these cards will probably be familiar with the "Black screen lockup" problem, The answer
in my case was to apply Jimmor's "Red wire link" mod as the Vid2 ground mod does not stop this happening.
Now my card is currently running stable at 516mhz Gpu and 1621mhz Vmem.

Any lucky dude who has a G71 based 7800gs should be able to get up to 700mhz Gpu speed as the G71 defaults to 1.1v
in 3d mode, so shorting Vid4 in that case gives 1.5v Vgpu.

Hopefully this helps some people out here as I couldn't find much on these forums about Volt modding 7800gs cards.
Of course keep in mind that doing any soldering on the pcb Like I did will immediately void the warranty.
I also eventually had to disable the Overclock Test in Rivatuner as it wouldn't let me go higher than 512 Gpu,
but would pass ram at 1700mhz, haven't benched at 1700 yet though.
Anyone interested in doing this should thoroughly read the forums I have linked to first as different
Brands of cards and varying hardware configurations may mean slightly different steps are required. What worked
with my card may not with someone elses, especially if a card deviates from Nvidia reference design.

 

[David]

Thanks for the info

PS Welcome to the forums.

 

[imperiousleader]

Thanks, I have been around for a bit over a Year though. Apparently
The next and final version of Rivatuner is going to have "the most deeply hidden and most wanted Easter Eggs ever available in RT!". Here's the Link
http://forums.guru3d.com/showthread.php?t=207440
Be awesome if it was unlockable pipes on 7xxx series Cards, but maybe
that's just a Fantasy.

 

[Frosty18]

I also have a 7800GS G70 I'm trying to overclock, a few questions for you..

My card will run at 565/1800 but I get the black screen thing you speak of. It's not a temperature issue, I was able to modify a P4 HSF and mount it on the card, temps never go above 46 C.

I don't quite understand what you mean by the default 1.1V. So if I am setting 1.8V in my bios for AGP that's not changing the Voltage on my card at all? The highest I can get stable without any volt mods is 522/1526. FYI, my ram overclocked better after removing the stock HSF and their thermal tape. I never even put ramsinks on the backside of the card, they're always cool to the touch.

 

[imperiousleader]

The 1.8 volts You have set in the bios is the Voltage for the Agp bus, it has nothing to do with the voltage supplied to the Gpu in your card. I suggest You go to the VRzone link and there is a picture there that shows the measure point for Vgpu, measure it with a multimeter and make sure You are running a 3d game, If that point measures 1.1v then You have a G71 based 7800, if it measures 1.4v then You have a G70 based 7800. Apparently all cards show as G70 in the Driver and/or bios. In the bios of my computer I set the Agp bus voltage to 1.6v , unless You are running the Agp bus in excess of 66mhz then there is probably not much point running 1.8v, also possible could do damage.
Thats great overclocks by the way, I was thinking of getting rid of that crappy looking thermal paper stuff myself and using some Arctic silver instead. Mine is all still stock cooling wise.

 

[funion]

From what I have seen the G71 cores are displayed as G71.
I knew about the mem mod but the core mod is news to me, thx for that.
Makes me wonder what I can push my card to with the mods.

 

[imperiousleader]

You may be right about the G71 cores, I was going on something I read on Guru3d forums, so can't verify that myself. Apparently the G70 cores can go up to around the 550 mark and G71 around the 700 mark.