all vmod for all 6800

[OnLine]

Before the mod max 400 on the core before artifacts and/or freezes, after the mod 436 on the core before freezes [ no artifacts ].
The freezes comes from FW.

This mod should be used in conjunction with the famous Bios V-mod [ 1.4V or 1.5V ] for best result.

The circuit isn't perfect, but it is functional.

*Warning, the mod is not fully tested yet

http://service.futuremark.com/compare?2k3=3588506

[stealthbomber]

Good work there, I'd use insulation tape (or hotglue) all the bare wirings/connections to avoid shorting out the card.

Are you gonna use the cards spare screw holes for fixing that sink with the mosfet's onto the card using dremel 'n some nuts and bolts?

[Del Gro Badeu]

wow, good job OnLine !!!

is there any possibilities for you to post more HQ pics ???!!! and how can you push up the core voltage with this mod ?

€dit : and do you think this mod can be adapted to 6800 NU / LE to provide a more stable core voltage ?

[OnLine]

Good work there, I'd use insulation tape (or hotglue) all the bare wirings/connections to avoid shorting out the card.

Are you gonna use the cards spare screw holes for fixing that sink with the mosfet's onto the card using dremel 'n some nuts and bolts?

Yeah I know what You mean, it's easy to shorting out things.
But I don't want to seal it, not yet because I've still some modifications to do.

I'm going to add 2 more PNP power transistors to stabilise the output/core voltage a bit.
As it is, the circuit should permit 6 to 8 A but I need more.
The highest stable voltage I can give my GT is still only 1.47V.
Anything higher, my card becomes less stable.

1.6V core voltage and fully stable at 450 core is my main goal.
Then I can seal it.

As for how to mounting it I've no idea, the heatsink can get pretty hot and it needs a fan.
But probably in a box, with a fan blowing on the heatsink lying at the buttom of the case.

Before the mod my GT refused to work properly with 1.4V.

'01 at 400/1100@1.4V before the mod ;

[Del Gro Badeu]

nice shot ^^

what cooling do you use on it ? it can be the origin of high voltage instability

[OnLine]

wow, good job OnLine !!!

is there any possibilities for you to post more HQ pics ???!!! and how can you push up the core voltage with this mod ?

-thanks !
Sure, more pictures to come !
1.47V, cooler Arctic silencer 5 ~ anything higher the card becomes less stable.
I've to modify the circuit a bit and probably add 2 more power transistors.
It's functional, not perfect. Not yet !

[Del Gro Badeu]

ok

i've edited my two previous post if you can get an eye on them it will be really cool

[OnLine]

ok

i've edited my two previous post if you can get an eye on them it will be really cool

" and do you think this mod can be adapted to 6800 NU / LE to provide a more stable core voltage ? "

- Yes !
Just find the soldering point for core voltage on your board.
In principal, this mod should work on any card

" what cooling do you use on it ? it can be the origin of high voltage instability "

That's true, however my temps are pretty fine even at 436/1205@1.47V, in the mid 60's I believe [ max 70 'C ]. Arctic silencer 5 is a great cooler.

Edit: my camera is crap, but I'll do my best.

[Del Gro Badeu]

the first answer is simply wonderfull

so, what we need ( and this on any card ) is to locate a core voltage point on the card ( it is done with cap mod for 6800 LE / NU ) and to solder it at this point with output set to normal core voltage at the beginning

wooowww really good job !

[Nosfer@tu]

it's a VT1103M from Volterra, if you want the name and the manufacturer of the devices.



any place will be ok, prefer the easiest ( not sure if this word is ok ) for you to done the mod

Sure it is mate

I will interpet that as " Just juse the most clean readpoint for your soldering " Think I will juse a 50 Ohms variabel resistor just to be safe

Also im ´really considering jusing a 3300 uf 10v cap.

If any of you have a link for Vmemmory mod I would LOVE that

Not much reason in doing the mod if I dont do that first :p

[stealthbomber]

Damn, I always go a bit nuts with the hotglue gun, just for good measure , not sure I can adapt the original mods without pealing the glue off first which will likely rip off all the soldering job...

Guess I'll just have to try out the 2x 12v molex mod...

[stealthbomber]

Edit: oops double post...

[OnLine]

the first answer is simply wonderfull

so, what we need ( and this on any card ) is to locate a core voltage point on the card ( it is done with cap mod for 6800 LE / NU ) and to solder it at this point with output set to normal core voltage at the beginning

wooowww really good job !

Pretty much, but I feel I must make a reservation.
The NU/LE has different layout on the board and uses different stuff [ like voltage regulators, capacitors ] and is probably over voltage / current protected a bit different.

So it may respond a bit different to this mod.

But I'm pretty sure it's safe, just remember before connecting Vout(+) to the board, to keep that voltage lower [ edit: or normal ] than your boards currently working core voltage.

Is that 1.2V or 1.4V for LE/NU ?

Edit: For the circuit to function properly the ouput voltage must have a load.
Which means, a 100 ohm resistor should be used as a temporary load when adjusting Vout[+], that is before connecting Vout[+] to the board.

[stealthbomber]

6800LE defaults to 1.1v, 6800NU is 1.2v

[OnLine]

6800LE defaults to 1.1v, 6800NU is 1.2v

That low !?

That means a 6800LE must first be Bios V-moded to use 1.2V before adding this power mod or else I predict some instability.

The circuit doesn't permit anything lower than ~ 1.25V [ thanks to LM317T ].
The difference between 1.2 or 1.25V shouldn't be a problem though.
One can safly set Vout[+] to 1.25V before connecting it to the board.

IIRC LE's/NU's can be Bios moded to use up to 1.4V core voltage, which is perfect.

[stealthbomber]

Well my 6800LE modded to 1.5v via bios is running fine 24/7 with the modded NV5...

[Bloody_Sorcerer]

ok, I've got a few questions here:
first, how/where do you do the BIOS vmod?
second, which voltmods here apply to the ASUS V9999GT/TD (700MHz DDR1)?
I'm curious about all of this because I believe that my RAM is undervolted, since its rated at 900 MHz but the maximum stable ("Driver passed the test") clock is 825, and the core maxes out at 375 at 1.35 volts.

[matt9669]

I don't know if anyone's looked at Vmodding the PCIe versions of the 6800 yet, but here are some semi-decent pics of my BFG 6800 GT OC (too big to post directly):

http://www.mattoverclocked.com/front.jpg
http://www.mattoverclocked.com/back.jpg

Hope that helps - I'm glad to whip out the soldering iron, but I don't have a PCIe board at the moment so I can't test anything (waiting on the DFI SLI - go NCIX!)

Interesting thing - the power supply portions of the board (at least the underside) do not seem to be missing anything compared to the Ultra - don't know how much effect this will have, or if it will make 1.4V safer . . .

[Jethro]

everything you need for bios modding is here: http://www.mvktech.net/

Ram is really underpowered on these NU's probably by design. When you get power to the ram the card really feels very fast. It has much more of an effect you can feel than raising the GPU voltage and speed. I recommend using NVbitor to mod GPU voltages. The green voltage is the one your card will use in 3d mode. With very cold watercooling i choose to set 2d/3d and low power 3d voltages all the same.

1.4 is optimal to get to 400+ 1.6v gets me to 440 which i believe is the max of my GPU your mileage may vary. The ram modding just seems to add much more snap either way.

Its very interesting that my NU handles voltage far better than the BFG did with its seemingly higher tech power circuitry.


I have a dead 6800GT by BFG and its missing several components vs an ultra including mosfets, molex, caps. Looking under the long slender heatsink you will see the primary reason they dont like voltage over stock.

[stealthbomber]

Jethro how did you manage to get 1.6v in bios, did you volt mod the card with an extra VR?

IIRC the bioses only allow up to 1.5v max on these cards.

[Bloody_Sorcerer]

Jethro: so what you're saying is that by correcting/boosting RAM voltage one would be able to pull alot more performance from one of these cards than by boosting GPU voltage?

[kryptobs2000]

On 6800LE's/NU's because the ram is limiting the ram is really craving voltage and the ram is holding the card back. The same would not apply on the 6800 GT or Ultra.

[Jethro]

No the Bios mod does in fact support 1.6v. download the latest nvbitor and see for yourself =) for some reason ASUS and EVGA bioses support 1.6v and perhaps some others i dont know as those 2 are the only bios's ive tried.

rivatuner definately reports the jump from 1.4 to 1.6 tho.

Extra ram juice makes my card feel alot faster than the going from 400 (1.4v) core to 440 (1.6v) yes. your mileage may vary.

1.4v GPU is a good balance to make card do 400 and be rock stable with 16pipes/6vertex IMO 1.6 is overkill and is very hard on ICS's while 1.4 to me seems perfectly safe with these cards voltage regulation IE no major hot chips!

[kryptobs2000]

I have found LM317T's no problem, but where did you get the MJE2955's at?

Also, could you type a full parts list to make sure I got everything. And changing what would make this mod better? Adding more caps I would think, can they be added anywhere, or should I just add them in a row or parralell with the 5000uf cap you have in the diagram? And I don't completely understand the diagram, could you explain how to read these maybe lol?

I know where the Vin (redwire) and the Vout (blackwire) go (to the molex), and the Vout (green wire) (to the solder point on the card), but where does the Vin (blackwire) go?

[OnLine]

I have found LM317T's no problem, but where did you get the MJE2955's at?

Also, could you type a full parts list to make sure I got everything. And changing what would make this mod better? Adding more caps I would think, can they be added anywhere, or should I just add them in a row or parralell with the 5000uf cap you have in the diagram? And I don't completely understand the diagram, could you explain how to read these maybe lol?

I know where the Vin (redwire) and the Vout (blackwire) go (to the molex), and the Vout (green wire) (to the solder point on the card), but where does the Vin (blackwire) go?

Instead of MJE2955 You can use 2N2955 [ they are the same only different manufacturers AFAIK ].
Vin (blackwire) = Vout (blackwire) = to the molex.
I've tryed higher rated caps [ they should be added in parallel btw ], but it didn't make a noticable difference.

As for Q1's pin layout look here: http://www.elfa.se/pdf/71/07100233.pdf
C1 doesn't have to be exactly 0.01 uF, more like anything between 0.01 and 0.1 uF. But use 0.01 uF if You can find one.

Follow the circuit, it is pretty simple.
Tomorrow I'll post a better picture.

* The mod is still under some modifications, it's far from perfect especially when using a core voltage of 1.5[+] V.

Edit: use separate heatsink for each power transistor [ Q1 ] and voltage regulator [ LM317T ] unless You have non-conductive thermal pads like I have [ see picture ]. The buttom of Q1 and LM317T is conductive = the mid pin. Without the pads those 3 heatsinks can't touch each others.