G80 8800GTS OCP + VDROOP MOD - Made & Confirmed Working!

I Have successfully made the OCP mod for the 8800GTS (G80). What you do is solder 1.2K SMD resistors across the 3 caps i have outlined in pink. The stock resistance across the caps was 1.29k and with the 1.2k SMD resistors on it is reduced to 0.61k. This reduces the OCP signal by 51%. I also realised during testing that it also reduces vdroop from ~0.08v to 0.02v under load. I successfully ran bench after bench @ 1.52v idle, 1.50v load. You will need to improve cooling though, i have a modded heatsink & fan and it still hit 93*C during repeated runs of 3dmark05 GT2 but it was totally stable. I was able to bench stable at 702MHz gpu, the previous max was 684, and theres more left in it.
No photos yet i had no camera :)

Enjoy :)

EDIT: pic 1 edited to show values. NB: replaced 70B is not part of the OCP mod.

EDIT - PICS OF MOD ADDED. Please excuse my soldering im not using a fine tipped iron and those smd's are tiny :)

EDIT: The vdroop is 0.02v, but for most of the time it is only is 0.01v :)

For the benefit of people like me who like to save images to be used later, can you edit your photo to show the mod values on the picture itself?

Good work though buddy!
Any ideas for Ultra?

Pic edited showing mod values :)

I dont own the ultra so i cant measure anything, & im actually having a hard time getting a nice pic of the px3540 controller area of the GTX/Ultra, so at this stage, no idea. I have seen people running pretty high voltages (1.5 - 1.6v) on GTX/Ultras so is the OCP mod really needed?
The Isen circuits must be similar as the GTS i have & the GTX/Ultra all use the PX3540 controller - the arrangement of the R/C circuit differs though. However if i had a nice pic to work from i could maybe help work it out (others would need to measure everything).

The mod is definately necessary for people like me wanting to run higher than the ~1.66V (idle) that the Ultra allows, and particularly if the mod reduces droop!
If you want a picture i'll post one up here.

I cant say i've ever seen a OVP/OCP/etc mod that required modifying a capacitor???

odd.

Quote:

---

Originally Posted by Timbosan

I Have successfully made the OCP mod for the 8800GTS (G80). What you do is solder 1.2K SMD resistors across the 3 caps i have outlined in pink. The stock resistance across the caps was 1.29k and with the 1.2k SMD resistors on it is reduced to 0.61k. This reduces the OCP signal by 51%. I also realised during testing that it also reduces vdroop from ~0.08v to 0.02v under load. I successfully ran bench after bench @ 1.52v idle, 1.50v load.

---

Hey, good work! :)
Did you notice any Vgpu change in 2D mode after soldering these 3 resistors?

PS The final scene of the Half-Life2 EpTwo is a very good OCP check! If you can try this with 1,52/1,50 V and OCP will not work - please tell us :)

fantastic work :)

how did you figure out what to do here

No wonder the PCB shot in 1st post looked familiar...
That's my pic from hipro's G80 OVP -thread.
:)

edit:
I guess it's worth mentioning the removed resistor "70B" (replaced with "472") visible in the pic is not a part of this mod.

Quote:

---

Originally Posted by N1ck R1mer

Hey, good work! :)
Did you notice any Vgpu change in 2D mode after soldering these 3 resistors?

PS The final scene of the Half-Life2 EpTwo is a very good OCP check! If you can try this with 1,52/1,50 V and OCP will not work - please tell us :)

---

Thanks mate. No there was no change in 2D voltage - i booted up and it was same as before the mod. I dont have HL2 on my PC, but i have gamed NFS Prostreet & crysis for 3 hours at 1.52/1.50v no probs. I can repeat (only tried 8 repeats so far) 3d03 nature, 05 & 06 with no problems. Also ran 1.57v/1.55v for about an hour no problems either.

Quote:

---

Originally Posted by dinos22

fantastic work :)

how did you figure out what to do here

---

Thanks. Well working it out was a matter of working out which R/C components were involved in the Isen circuit, as the design differed from the G92 in that there is only one resistor paired with each cap in each phases Isen circuits. Soldering the resistors in parallel across the caps in theory should reduce the signal the primarion controller is seeing by a certain amount, depending on the value of the resistor used. The stock resistance across the cap was 1.29K so i didnt want to go much under 1.2k value so as to keep the signals still usable for the controller to keep current balance between the phases equal. I was initially going to use VR's adjusted to the same value but opted for SMD resistors. With the 1.2k smd's, its about a 51% reduction in signal,, which should be enough for some serious voltage.
I also have to thank Viper John, who helped me work out how the R/C circuit worked.

Quote:

---

Originally Posted by largon

No wonder the PCB shot in 1st post looked familiar...
That's my pic from hipro's G80 OVP -thread.
:)

edit:
I guess it's worth mentioning the removed resistor "70B" (replaced with "472") visible in the pic is not a part of this mod.

---

Yes i reappropriated your pic :), i had no access to a camera till today. And yes, the removed 70B resistor replaced with the 4.7k is not a part of this mod.

That's great news, thanks for sharing.
I think it's time to finally mod my GTS, results should be great since it does 730 core with stock 1,24V - it's watercooled with a Heatkiller GPU-X though so it doesn't reach more than 45C diode.
I think improving your cooling would get you way better clocks - my card could only do 670 core or so with stock fan, reaching 90C...

Quote:

---

Originally Posted by dinos22

fantastic work :)

how did you figure out what to do here

---

He emailed ViperJohn lol.

Viper

Quote:

---

Originally Posted by ViperJohn

He emailed ViperJohn lol.

Viper

---

Quote:

---

Originally Posted by Timbosan

I also have to thank Viper John, who helped me work out how the R/C circuit worked.

---

Sorry mate i should have made more of a point of it. Viper is very knowledgable, and was extremely helpful regarding my questions and his explanations. Without his help i would have first soldered VR's on the caps (wouldnt have worked well if at all) and failing that was considering removing the caps altogether (with disasterous consequences).

Thanks mate :up:

I should also add that i replaced my 20k vgpu VR with a 1K VR - this fixed my excessive droop when at certain voltage settings. I now have 80% of the time 0.01v droop, and in the heaviest scenes 0.02v droop.

I also think this mod could be adapted for the GTX and ULTRA cards also using the px3540 controller.

Quote:

---

Originally Posted by jcool

That's great news, thanks for sharing.
I think it's time to finally mod my GTS, results should be great since it does 730 core with stock 1,24V - it's watercooled with a Heatkiller GPU-X though so it doesn't reach more than 45C diode.
I think improving your cooling would get you way better clocks - my card could only do 670 core or so with stock fan, reaching 90C...

---

that sounds like its an A3 revision then (clock better than the A2's like mine), and yes i have to do something about my cooling, im stable at 702 until GPU reaches ~97*C. Thats why i cant test this mod over about 1.55v as it hits 95*C in one run of 3DM03 nature.

Yeah it's a Zotac A3 :)
What I am very interested in now is how much shader clock you gained by Vmodding?
I'm planning to hit no less than 800 Core, maybe 850 - but what about the shader? 2Ghz would be nice, atm I'm at about 1780 :)
0,02 max Vdroop sounds nice, I currently have 0,04V droop measured with ATITool running (1,28 idle).

this mod is for water at the very least
better cooling is needed to make use of xtra volts
700 on core shuold be easy with just vmod on a2's
i'v run to 770 on 1.28v with all three of mine
card temps 28c-46c
but great work and thanks!

770 with 1,28V load? That's encouraging, so 850 might be possible with ~1,4V :)
How about the shader clocks, do they improve at all after doing the mod?

a2 just using a modded stock heatsink 1.28v
at the time no way to indepently change shaders
http://aycu14.webshots.com/image/176...1042954_rs.jpg
cool temps is key
a3 same 1.28 with much better temps
http://aycu07.webshots.com/image/268...8522379_rs.jpg
with either if i dont have the cards cooled well 700 no matter what.

Erm.. that was using modded stock cooler? Either u live in the Arctic or ur air conditioning unit is a bit overpowered :D
Seriously, do you think 45C diode is already too much?
I mean, it's half of what most people are running, and 730 is stable and artifact free@1,24V...
And by the way, fine-tuning shaders has always been possible using a modded bios ;)

so...izzit work with GTX ???
clearer picture for GTX version..
i've no luck on hipro mod...i wud like to try this out...
GTX OVP kicks in bout 1.55-1.6v

Quote:

---

Originally Posted by hehee

so...izzit work with GTX ???
clearer picture for GTX version..
i've no luck on hipro mod...i wud like to try this out...
GTX OVP kicks in bout 1.55-1.6v

---

If you did hipro's OVP mod and it's not enough, you should get rid of the OCP. The problem is - GTX has 4 phases, so you need 4 SMD resistors, but the schematic of GTX and GTS power converters differs.

Quote:

---

Originally Posted by jcool

Yeah it's a Zotac A3 :)
What I am very interested in now is how much shader clock you gained by Vmodding?

---

Keep in mind my A2 rev wont clock as high as your A3, but I was at 1620 before the mod now i can do 1782 but once it core is 95*C+ it starts to artifact. If i could keep temps under ~70*C i think 1782 - 1890 would be possible.

Quote:

---

Originally Posted by cowie

a2 just using a modded stock heatsink 1.28v

---

Thats a very low temp with a modded stock HSF. What was the ambient temp?

Quote:

---

Originally Posted by hehee

so...izzit work with GTX ???
clearer picture for GTX version..
i've no luck on hipro mod...i wud like to try this out...
GTX OVP kicks in bout 1.55-1.6v

---

as nick said you would need to mod 4 SMD caps rather than the 3 seen here, and the design differs so the locations are different & the values of SMD resistors used would also probably be different for the GTX.
It should be adaptable to GTX or ULTRA though, need someone with one to measure things as i dont own one, and take a punt on doing the mod.
I'd love to see an ultra running 1.7v+ on DICE or LN2 :)

Ah great, so 2Ghz shader might be possible after all :)

2ghz im honestly not sure, ive never seen an A3 GTS modded & OC'd, but 1800+ should be a gimme with vgpu mod, even air cooled. 1900 - 2000+ not sure.

Did this:

http://images.people.overclockers.ru/preview/145278.jpg

The resistors are above caps, so caps are invisible at this view.

Bad news - the OCP still works with HL2Ep2, at the same 1,38 V.
ATi Tool, Crysis and all of 3DMark's goes fine with 1,45 V and 729 MHz GPU, but HL2 final scene shuts my PC down, as it was earlier.

Quote:

---

as nick said you would need to mod 4 SMD caps rather than the 3 seen here, and the design differs so the locations are different & the values of SMD resistors used would also probably be different for the GTX.
It should be adaptable to GTX or ULTRA though, need someone with one to measure things as i dont own one, and take a punt on doing the mod.
I'd love to see an ultra running 1.7v+ on DICE or LN2 :)

---

i really looking forward for a mod tat can make mine GTX go over 700mhz...685mhz was max for me...
but i'm electronic idiot...only can do solder....

Quote:

---

Originally Posted by N1ck R1mer

Did this:

http://images.people.overclockers.ru/preview/145278.jpg

The resistors are above caps, so caps are invisible at this view.

Bad news - the OCP still works with HL2Ep2, at the same 1,38 V.
ATi Tool, Crysis and all of 3DMark's goes fine with 1,45 V and 729 MHz GPU, but HL2 final scene shuts my PC down, as it was earlier.

---

Perhaps it is due to the fact that you removed the other resistors (i have not), without which the px3540 will most likely register a fault and have unpredictable consequences. Also, as the signals are used for controlling vgpu PS bias (droop) as well as current sharing between the 3 phases, Its even possible you are overloading one or more of the phases. Unless you replace the removed resistors, the results cannot really be compared to my mods results.

I have gamed crysis/nfs pro street @ max graphics settings (no AA) for hours at 1.50v load. I find it difficult to believe that these games at 1.50v load would pull less current than HL at only 1.38v load.

Can you run repeats of 3dm03 nature & 3dmark06 at 1.55v load?

Quote:

---

Originally Posted by Timbosan

Perhaps it is due to the fact that you removed the other resistors (i have not)

---

Yepp, i did

Quote:

---

Originally Posted by Timbosan

I have gamed crysis/nfs pro street @ max graphics settings (no AA) for hours at 1.50v load.

---

I've played Crysis for 1,5 Hours with 1,45 V & 729 MHz - all works fine.

Quote:

---

Originally Posted by Timbosan

Can you run repeats of 3dm03 nature & 3dmark06 at 1.55v load?

---

I did this with 1,5 V and it works, so 3dmark is not the stability test at all. Could you please try HL2EP2? If you do not want to walkthrough the game, here's my save: http://www.filefactory.com/file/1de604/. You need about 3 minutes (with 1280x1024xAll High) to test, if there is no OCP there - this will be the conclusive proof.

P.S. Just for informaton - the 78X resistors are 63,4 Ohm each.

Quote:

---

Originally Posted by Timbosan

2ghz im honestly not sure, ive never seen an A3 GTS modded & OC'd, but 1800+ should be a gimme with vgpu mod, even air cooled. 1900 - 2000+ not sure.

---

I can run 1780 stable as it is, 1820 benchable but producing artefacts.
So - why not? I'm gonna do all the mods as soon as I find the time and report back here :)

Quote:

---

Originally Posted by N1ck R1mer

I've played Crysis for 1,5 Hours with 1,45 V & 729 MHz - all works fine.

I did this with 1,5 V and it works, so 3dmark is not the stability test at all. Could you please try HL2EP2? If you do not want to walkthrough the game, here's my save: http://www.filefactory.com/file/1de604/. You need about 3 minutes (with 1280x1024xAll High) to test, if there is no OCP there - this will be the conclusive proof.

P.S. Just for informaton - the 78X resistors are 63,4 Ohm each.

---

I asked if you could bench @ 1.55v, not 1.45 & 1.50v. Again today i benched 03 nature & 06 at 1.62v idle 1.60v load - can you do that? (dont say you did at 1.5 and its the same as my 1.6v as its not ;))

im still not convinced, what you did by removing the 78X resistors is crazy and may be causing your problem. Your phase current sharing may well be out of whack and possibly other factors too. After removing the 78X resistors, i dont see why you added resistors across the caps - the OCP mod needs the 78X resistors to remain in place & the Isen circuit to be complete and functional.

Did you measure the resistance across the caps & to ground before and after soldering them on? Or did you just solder on 1.2k's as thats what i did? I measured mine & thats why i chose the 1.2k resistors - since you removed the others it may be you need different value to me, or need to replace the 78X resistors to retore functionality.

The mods are not the same, therefore not comparable. You may be running at totally different resistances, if the Isen circuit is even still active & functioning correctly on your card. Replace the removed resistors buddy, then say it doesnt work ;)

Despite your result, i could never run above 1.45v idle no matter what the test or game before it would shut down, so it has achieved a substantial gain for me.

i will be busy till at least 2nd Jan, may download & install game after then.

Quote:

---

Originally Posted by Timbosan

I asked if you could bench @ 1.55v, not 1.45 & 1.50v. Again today i benched 03 nature & 06 at 1.62v idle 1.60v load - can you do that? (dont say you did at 1.5 and its the same as my 1.6v as its not ;))

---

Mark's is NOT the stability tests with 8800XXX series! The OCP works at 1,38 V now and it it's no matter if it 1,5 or 1,55 or 1,6 V - it works with HL2. I can run "nature" test even with current 1,37 Volts and 729 MHz GPU, but HL2 will freeze in about 5 minutes, so "nature" is not the stability parameter.

Quote:

---

Originally Posted by Timbosan

im still not convinced, what you did by removing the 78X resistors is crazy

---

No, it isn't. That's the way how OCP mod's working - you should isolate sense pin(s). That's the way, how is has been made with 7900GTX and the other cards. And now we know that it's the way to remove OCP with 8800GT and new 8800GTS 512 M.

Quote:

---

Originally Posted by Timbosan

and may be causing your problem.

---

Yes, this could be. I did not throw out those resistors, so I can place them back any minute. You said that you ran marks and Crysis with more than 1,38 V - so do I, and I notice NO any OCP. That's why the 78X resistors are still in a polyethylene separately from my card.

Quote:

---

Originally Posted by Timbosan

Did you measure the resistance across the caps & to ground before and after soldering them on? Or did you just solder on 1.2k's as thats what i did? I measured mine & thats why i chose the 1.2k resistors - since you removed the others it may be you need different value to me, or need to replace the 78X resistors to retore functionality.

---

Yes, I did. It was about 1,29 K.

Quote:

---

Originally Posted by Timbosan

Despite your result, i could never run above 1.45v idle no matter what the test or game before it would shut down, so it has achieved a substantial gain for me.

---

Yes, It's about 1,38 V load. I did the whole HL2EP2 walkthrouh with 1,45 V load (it's the min voltage for 729 MHz core with my card) and OCP works only at final scene. Then I tryed another apps (also the Crysis - no effect), and found one, which causes OCP with 1,45 V idle - it's the Bioshock game. But it needs about an hour that protection has worked.

Quote:

---

Originally Posted by Timbosan

i will be busy till at least 2nd Jan, may download & install game after then.

---

If you did this and notice no OCP with at least 1,45 V load (don't need 1,6 V esp. with stock cooling!), please post your impressions here :fact:

I still think your problem lies with the removed 78X resistors. However i have bioshock installed, i will try to play it for at least an hour with 1.50v load & see how it goes.

When i return from NYE celebrations, i will get HL2EP2 and try it, beacause if it causes higher current draw than anything else, it would be a good test. Im sure many people would be interested in using it as a test if this is true. Maybe even nvidia are wrong, as afaik they repeat the nature scenes from 01 & 03 to determine max current draw. If there was something better i would have assumed they'd use it. Regardless, ill give it a go.

Have a good NYE im out till the 2nd :)

Quote:

---

Originally Posted by Timbosan

When i return from NYE celebrations, i will get HL2EP2 and try it

---

I'm waiting :yepp:

Quote:

---

Originally Posted by STEvil

I cant say i've ever seen a OVP/OCP/etc mod that required modifying a resistor???

odd.

---

This info is allready 2 months available, you need a catchy thread title those days to spread the news? Anyways, I threw some of my gathered info online at the VR-forums.

No thanks ;)

http://forums.vr-zone.com/showthread...=189621&page=2

lol, I meant capacitor.....

N000000000!!!!!!!!
can't let... thread die
I've got a 8800gts ssc (just like a 8800gt with 640mb/320bit, and 112 shaders)
It's an a2, and an unusually bad overclocker. I can only get to 650/1566/970 (stable) with vmods, and a heavily modified stock cooler. I think this is because the ssc version draws more power which sets off the ocp alot earlier than normal. (1.35 (1.29 ish load) will turn the thing off during bouts of 3dmark 06. I need to do this mod. Does radioshack carry these smd resistors? What would happen if i used one with slightly different resistance? Also i know this is probably a pretty dome noobish question but if there was a point were all three of those resistors link up where you could just install a pot (i've got plenty of those lying around, lol)
Thanks

fragmasterMax,
There is no "link up point" so you can't use a single pot to do the mod. Btw, the resistors do not need to be SMD. 3 linear resistors (or pots) would do the same thing as long as they're ~1.2kΩ. 1.2kΩ is not a figure set in stone, a lower R value would weaken the OCP (and vGPU phase balancing) even more compared to 1.2kΩ, higher R -> vice versa. Higher R is only more safer, but a considerably lower R might be a bit more riskier. Don't go by a "too" low R value, though...

Quote:

---

Originally Posted by largon

fragmasterMax,
There is no "link up point" so you can't use a single pot to do the mod. Btw, the resistors do not need to be SMD. 3 linear resistors (or pots) would do the same thing as long as they're ~1.2kΩ. 1.2kΩ is not a figure set in stone, a lower R value would weaken the OCP (and vGPU phase balancing) even more compared to 1.2kΩ, higher R -> vice versa. Higher R is only more safer, but a considerably lower R might be a bit more riskier. Don't go by a "too" low R value, though...

---

Great
thanks for the valuable info.
15k in 3dmark 06, here i come. I'll try it with some of these pots i have, and see if lower resistance than 1.2k gives me different results. I have Friday and sat off, i'll report back with my results.
I can't wait to see what kind of results this will yield.
WAIT
what do you think would happen if i just used one pot and connected all three
caps to it? (and connected the output of the pot to each one of the grounds on each of the caps?
would that F*** things up? It seems likely that it would. What do you think?
Thanks!!!!!

Your gambling a gfx card that costs hundreds of dollars over buying some resistors that cost pennies. Go online and order some SMR's and do it right!

Quote:

---

Originally Posted by jason4207

Your gambling a gfx card that costs hundreds of dollars over buying some resistors that cost pennies. Go online and order some SMR's and do it right!

---

you've got a good point.I'll see what radioshack has to offer, in any case i want to get this done asap. (no waiting for shipping).

Would replacing the caps, and adding different ones have any effect?
here's something interesting from wikipedia btw:
Capacitors are used in power factor correction. Such capacitors often come as three capacitors connected as a three phase load. Usually, the values of these capacitors are given not in farads but rather as a reactive power in volt-amperes reactive (VAr). The purpose is to counteract inductive loading from electric motors and fluorescent lighting in order to make the load appear to be mostly resistive.


Theres plenty of food for thought, but right now i need sleep. :yawn2:

I completed the mod with 1kohm (1/8 watt) carbon film resistors that i picked up at radioshack for a grand total of .99 cents. (they came in a 5 pack.)
.....and it worked out great though i am still a bit disappointed in the video card that i have. Before where i was able to get to 650/1566/970 now i am at 650/1782/970. I could only get the vcore at 675 when i pored on the volts (1.5 and above At that point the themps where in the mid 80's). One thing is for sure, the shader clock runs off the same voltage as the core, so the higher that is the more mhz you can pull out of it.

15k in 3dmark 06 was a bit of a stretch, i get 13440 with my b3 q6600 at 3 ghz. I'l see what i can do with a g0...........

THANKS GO TO TIMBOSAN FOR HAVING THE COURAGE AND INSIGHT TO DISCOVER THIS MOD!!!!!!!!!!!!!!!!!!!!!!!!!

Hey guys, thanks for the kind words fragmasterMax, i appreciate it. i have bad news. On friday, theives broke into my home and stole my system, and my older system, my laptop & other musical equipment, my multimeter, my mothers engagement ring, and other personal items. i now do not own any computers. im also not working right now, so a replacement will be a long time coming. upset doesnt come close to describing how i feel.

N1ck - im sorry but ill never know if my 8800 could run HL2EP2. I hope you persevere with the mod and sort out whatever issues your card has.

Seeya guys, i'll still be dropping in (from my friends pc though so it wont be frequent) so i will still answer anything you wanna know.

Tim.

:( :( :(
I hope the police catches them scum and you get your stuff back.
Maybe you should start watching "for sale" ads for your stuff just in case they try to flog the parts in a hurry? Sometimes they are that stupid...

:(

Sorry to hear about your lose man. There is nothing I despise worse than a thief. :shakes:

I hope they catch the a-holes and cut their hands off!

check pawn shops.

I got a question... I modded my cousin's 8800GT card and measured the voltage under idle and load....

I am not sure if we're measuring it wrong but at Idle it was 1.33v and under ATI Tool load, it shot to 1.38v.....

That's not exactly a vdroop...can anyone elaborate on this?

bad news mate :(

Quote:

---

Originally Posted by STEvil

check pawn shops.

---

^^^^he's right normally stuff like that pops in there

http://www.radioshack.com/product/in...entPage=family

can these resistors be used instead for the ocp mod? does it matter if it is carbon film or any type of film will work? thanks. Just not sure if I can get smd ones in town and I want to do this mod tomorrow.

Quote:

---

Originally Posted by n91htmare

I got a question... I modded my cousin's 8800GT card and measured the voltage under idle and load....

I am not sure if we're measuring it wrong but at Idle it was 1.33v and under ATI Tool load, it shot to 1.38v.....

That's not exactly a vdroop...can anyone elaborate on this?

---

sure can its normal all the G92 cards have positive vcore bias (voltage increases) under load.

Quote:

---

Originally Posted by dinos22

bad news mate :(




^^^^he's right normally stuff like that pops in there

---

Yeah i plan to do this. i have rung them all but i know they probably wouldnt be straight with me. its probably gone to dealers in exchange for drugs but theres a chance some of its been hocked.

Quote:

---

Originally Posted by zbomb5610

http://www.radioshack.com/product/in...entPage=family

can these resistors be used instead for the ocp mod? does it matter if it is carbon film or any type of film will work? thanks. Just not sure if I can get smd ones in town and I want to do this mod tomorrow.

---

they should be fine they have a lower resistance than mine but if you have a G80 GTS it should work although you will have a slightly higher OCP point than me (i never got a chance to check where it was on my card though). Any type should be fine, i just used 0603 size 1.2K smd's cos i had a spare mobo i desoldered them from and they fit perfectly.

I do not like solder VGA cards so i tryed to make a pencil mod. I could go only to ~1Kohm and that is not enought. My card still power down themself when I try to increase voltage.
May be I will buy some resistor and solder it...

Hey guys,
card's soldered and ready for some fun. Will be reinstalling it now and see how it goes - had a friend of mine do OVP/Vdroop as shown in this thread and also vgpu and vmem variable via poti :)
2000Mhz shader on water is about to go down!

Ok, Vdroop mod seems to work, I now have 1,34-1,35V idle and 1,33-1,34V atitool load :)
First tests schow an increase in OC potential, I got 756/1820 artefact free.
Next stop: 800 Core (I hope).

Edit: Got some bad news... seems like A3 cards don't like that much voltage. When I try 1,5V I get lots of artefacts in ATItool, also 3DMark06 in 1920*1200 freezes on me with 783Mhz core no matter the voltage :(
I don't think its OVP it's just the card that can't handle that much V. It's not too hot either (50C diode).
Also my mem sucks, I got 2160Mhz stable and artefact-free with 2,05V but when I try 2200 it fails. More V doesn't help but makes it worse, at 2,1V Vmem I even get more artefacts that at 2,05V - again it can't be the cooling, ram temp is under 40C.
As for the shader, 1890 seems the max (at least with 1,4V load). 1944 gives me lots of errors.
So for now I'm perfectly stable at 756/1890/1080, I did manage a 783 core run in 1280*1024 though :)

http://home.arcor.de/partywg2/Pics/3dm06_GTS.jpg

>15k with one GTS and a moderate 3,5Ghz CPU isn't too shabby I'd think :)