8800GTS 512Mb (G92) vMods

[VoRtAn_MaDgE]

I have only tried to lower the vmem . Right now it's at 1.92v .I got the mod from jason4207 via PM , but i haven't asked him if i can publish it . The best way is to send him a PM for information . I don't either like this "secret" mod , but it's not my choice since it wasn't me who found it .

Right now i have the card watercooled with vgpu & reverse vmem mod . Vgpu is at 1.40V idle / 1.45v full load . I can bench at 950/1080Mhz everything . I haven't tried much , cause my proper benchmarks will be with both CPU & GPU in my singlestages( when i get some time though)
Yesterday i put some heatsinks at the voltage regulators (they were very very hot) ... no time to check for gains .

I guess i've already found it on my own...
Digged almost 1h30 through pdf and multimeter reading but i guess i'm correct now!

Gonna take a picture of my card and publish it here...of course is untested but i guess it's ok to put it here...if someone that already have it wants to confirm...be my guest!

Next...shutting off pc, taking my card off, picture, photoshop and upload.

Be right back

[jason4207]

The "vmem buck" (or "reverse vmem mod") is not "my" mod. The credit goes to Viper John. Credit also goes to him for the OCP mod on the GT.

I have simply forwarded the info John gave me to others via PM. I believe John has a link in the bottom of his posts if you need help on any of these mods. He's the one that really understands this stuff well. I can understand it once he explains it to me, but until then I'm still very much a novice. I am learning, though, and I have a BS in Computer Engineering, so I'm not completely in the dark.

I really don't like all this secret stuff either, but it's not my mod.

I'm waiting to get my GT back from RMA, and then I plan on doing the vGPU, vMEM buck, and OCP mod to it and putting the HR03GT on it. I might post up a nice thread on it once everything is up and running.

I'm debating modding my GTS-512. I paid $360 for it, and I might save it for step-up in a couple months. We'll see.

[Stelios]

The "vmem buck" (or "reverse vmem mod") is not "my" mod. The credit goes to Viper John. Credit also goes to him for the OCP mod on the GT.

My mistake i forgot it ... Viper John found these mods !

[aussie-revhead]

team-eva doesnt exist??
We are very much a family at i4memory, not a one man band.

T_M , ..... rant removed .... sure thing buddy .

Dont bother with ram sinks for this card

This pic shows an area where the factory heatsink contacts some other chips , you dont worry about sinks on these ? With you running LN2 you probably freeze the whole card , but on air or water , and particularly with volt mods in place should these be heat sinked ? Or dont they get that hot ?

I just read a review and saw that the factory oc cards are running at 804/1080 , is this right ? I dont think I have seen a factory oc card that comes so close to the cards actual limits , usually even a factory oc card has a decent amount of headroom , but these dont seem to . I have also read of some guys that have problems with stability at clocks similar to the factory oc , does that mean these might be binned ?

Second pic shows a card from this forum with heatsinks fitted ...

[4Qman]

Im sorry but im a little confused.

I am at 915 core 1.39v IDLE 1.47v LOADED on stock air low ambient. BUT my memory craps out at 1040 and its reading 1.94v

SO......
Do i need to do Vmem mod and increase voltage to improve or lower to get better memory speeds?

Thanks

[T_M]

gotvoltage, 1.6V max sounds about right for max volts loaded.
Mine is 1.505V overvolting to 1.6V, and more than that is shutdown.

[aussie-revhead]

This pic shows an area where the factory heatsink contacts some other chips , you dont worry about sinks on these ? With you running LN2 you probably freeze the whole card , but on air or water , and particularly with volt mods in place should these be heat sinked ? Or dont they get that hot ?

T_M , would you be able to answer this for me please ?

[T_M]

I have not sinked anything at all on the card, but when on DICE/LN2 i have a strong delta blowing onto the power circuitry

[Zeus]

Are there any components that need extra cooling if you're going to push some more Vgpu?

I will put an EK fullcoverblock on it so i think the core-side of the card will be cooled properly.

[Trust]

Owners of 8800GTS (G92), please try to help me: http://www.xtremesystems.org/forums/...d.php?t=171215

[VoRtAn_MaDgE]

Are there any components that need extra cooling if you're going to push some more Vgpu?

I will put an EK fullcoverblock on it so i think the core-side of the card will be cooled properly.

Mem's, power circuit and there's also a ic on the back of the card that gets hotter than the rest.

Negative temps have a major impact on pcb temp...that's why users with that kind of cooling don't worry with that issue.

[Zeus]

VM, thanks, i will poke around with my indexfinger on the back feeling what needs some extra cooling.

Just did the Vmod for GPU with a 1K pot i had laying around, works fine but it's hard to get it stable when temps go over 50ºC.

Had 850 core 2000 shaders with 1.3V (load- so 3d voltage) but got some yellow dots in ATI tool, dang fan was at 100%, loud as hell.

I'm sure watercooling will take care of that.

What do you get with the stockcooler?

[VoRtAn_MaDgE]

VM, thanks, i will poke around with my indexfinger on the back feeling what needs some extra cooling.

Just did the Vmod for GPU with a 1K pot i had laying around, works fine but it's hard to get it stable when temps go over 50ºC.

Had 850 core 2000 shaders with 1.3V (load- so 3d voltage) but got some yellow dots in ATI tool, dang fan was at 100%, loud as hell.

I'm sure watercooling will take care of that.

What do you get with the stockcooler?

When you go above 1,35v gpu take care using 1kohm...little bit more difficult to jump volts in small steps...take more carefull turning the pot.

On air (stock cooled) 900 (almost reaching 910) is possible with a good core and 1.45 (loaded) or more...depends on each vga of course!

above 52, 53ºC it's hard to stabilize the vga aircooled...wc gives a much big advantage playing around with this card cuzz the difference for stock cooling loaded is huge....

There are also aftermarket good aircoolers for those babies...but wc it's a must when it comes to loaded temps!!!

I'm considering getting an external radbox system with watercooling just for single vga/sli, crossfire system... just need to update waterblock in the future .

Don't need it internal cuzz i don't use any case... like to use the hole system + prommy on the desk

[aussie-revhead]

Can I use a 500 ohm VR as T_M suggested ? Will this make adjustment easier ? I used it on my GTX but the voltages were way too high so I had to remove it , so I have a spare laying around .

[Zeus]

500ohm VR will make it a little less "jumpy" when adjusting over ~1.35V.

When you're using 1K VR you have to be more carefull turning the pot cause a little dial means more voltage than with a 500ohm over ~1.35V.

I did set my 1K VR to 500ohm before soldering so a 500ohm VR is even better than 1K actually.

[aussie-revhead]

How much core clock do you get with ~1.35v ? At what point do I need OVP mod ? Im about to search for it but could you point me to the OVP mod ?

[Zeus]

I think it depends on your cooling, anything over ~50ºC isn't stable for me, i'm waiting for my waterblock to arrive so i can get temps to decent levels, mine idles at 58-60ºC with the stock cooler, stock volts.

In a cold ambient with 1.35V you should see around 850 core i reckon.

Overvolt protection kicks in around 1.6V so unless you're planning to go xtreme there's no need to mod for that.

[aussie-revhead]

Cool !!

I wasnt planning to go that high as I dont really want to fry it up , but a little vmod fun wont hurt

I am planning a two stage mod with a small jump for 24/7 use and a large one for benching . I had this on my last GTX and it worked well . My G92 games fine at 800 core so far and benches up to 820 , so I hope I get more than 850 at 1.35v.

[T_M]

To avoid some possible missunderstanding:

OVP = Over voltage protection (typically if you reach this point the system will freeze/reboot even with no load)
OCP = Over current protection (typically if you reach this point the system will freeze/reboot only under load)

On G92 8800GTS, what we see is likely (i havent tested) to be OCP, which kicks in around 1.6V and high clocks under load.
This is not the idle voltage however, due to overvoltage under load, so you actually can only max out your voltage to about 1.5-1.525V idle.

[Zeus]

So here is 850 core 2100 shaders with 1.35V and stockcooler fan at 100%but becomes unstable over >50ºC:

[nickless]

If there is allready a pencil Vmod, can someone post a pics?!
Thanks!

[aussie-revhead]

Thanks T_M , that explains it perfectly .



Kako si Nickless - Im pretty sure no pencil mod exists , not yet anyway .



I finished my volt mod last night but that vgpu point is hard to see even with the magnifying glass ... The EK block will go on today .....

[Zeus]

Thanks T_M , that explains it perfectly .



Kako si Nickless - Im pretty sure no pencil mod exists , not yet anyway .



I finished my volt mod last night but that vgpu point is hard to see even with the magnifying glass ... The EK block will go on today .....

Stop!!!

If you dailed that VR to 500ohm, it will be 0ohm on the other end, meaning putting the switch in the wrong position results in 0ohm and way to much volt on the feedbackpin of that chip which could possibly kill your card!!

Why did you use both "variable" legs on the VR?

I always cut of one of te outer legs of the VR so i won't make a mistake.

I hope it's not too late.

That block is lovely, i ordered it december 19th but still haven't got it.

To anyone who knows: Is there any difference in overclocking between the lot of bios versions that are out there, or does a different bios number just mean a different vendor?

edit: on a closer look it seems like you are using 2 VR's stuck onto each other?

[jason4207]

It looks like the VR has 2 legs at each of the 3 positions. And it looks to me like he can switch the mod on and off. Middle is 'off', and either direction results in 'on'.

[Zeus]

It looks like the VR has 2 legs at each of the 3 positions. And it looks to me like he can switch the mod on and off. Middle is 'off', and either direction results in 'on'.

My guess is that it's 2 VR stuck together so that he can set either position of the switch to a diffent value.

For example, switch to the left is 1.35V and to the right is 1.5V, the middle is off.