TWINTech 9800GT Volt mod

[gomunkul]

Hello !!!

I came here seeking help with volt modding my NEW Twintech 9800GT.
GPU-Z reports its a 65nm core so if i'm not mistaken its the same as 8800GT (?)

*its a has 3 voltage regulators somehow.

*** i looked at the 8800GT pictures, i think my card 9800GT is a different design...

PLEASE explain how much as you can about volt modding, how do you know what to connect to what ?!

and if i can use regular resistors not variable ? i cant find those..

pictures:


















THANK you in advance!

[largon]

Measure resistance between red dot and ground.



How does it work?
The most common way volt modding works is by tampering the feedback mechanism of the vGPU phase controller (in this case, STMicroelectronics L6713A). Basically you need to make the controller think that for some reason vGPU is lower than it actually is, therefore the controller starts to compensate -> voltage rises. There are other ways too, but as usual, in this case the traditional "FB-pin spoof" is the easiest, and allows easy on-the-fly tuneability of the vGPU voltage if a variable resistor is used.

edit:
Double posting the request is not nice.

[gomunkul]

hi largon,

explain please how did you decided to check the resistance in this point and not the other?

*what can i use for ground? maby the metallic case? (a long time has passed since i learned electronics in school..)

*will measure it tomorrow, need to get my multi-meter.

***sorry for the double posting - deleted the other post, had to try getting an answer in several places..

[largon]

Red dot is connected to FB pin, which is the pin that the controller uses for feedback.
Any ground works, my recommendation is the PCIe power plug on the card.

Oh, and do the measurement on an unpowered card.

[bartx]

I have card with the same chip controlling Vgpu - http://www.xtremesystems.org/forums/...d.php?t=196707 You can find there, how I did this (but not use the same trimmers as mine, it depends on resistance on your card).

[gomunkul]

Good evening, finally got my multimeter:

measured the resistance from the red point to the ground = 1.125 K Ohm

http://www.xtremesystems.org/forums/...chmentid=86534

largon, what should i do next?
how much resistance (Ohm) i need to put between the red dot and ground?
and can i do it with several regular resistors?

Thank you in advance!

*bartx - i don't really understand how can i aplly what u have done with your card to mine..

[bartx]

I attached this link, because you can see there, where I can soldered wire and where can be measuring points. If it's your first mod, I thought that it can be helpful You resistance is almost the same as mine, so use 20k trimmer (or 50k, regulation would be worse, but starting voltage a little lower). I don't recommend regular resitors, because you can't change voltage, when card is running. If you would have trimmer, just make 1-2 turns and check the voltage. You can find measurements point on the back, try to measure SMD capacitors, or these three mosfets below L6713A chip (or somewhere there ).

[gomunkul]

if you have the same resistance, can you measure what resistance you have on your trimmer with the higher voltage (what voltage have you set)?
and i just add a resistor with the same resistance?

P.S: where do i measure GPU voltage on my card?

[largon]

Solder the resistor between the red point (or any parallel spot) you measured the resistance from and any ground on the card.
For example, if you add a resistor rated 15kΩ you will gain +8% to vGPU,
9kΩ -> +13% and
4.5kΩ -> +25%.

BUT, I would strongly recommend a 20kΩ variable resistor.

Some vGPU measuring points:

[gomunkul]

Thank you largon!

after trying several resistors, starting from 10Kohm I finally stopped on 5Kohm to get a GPU voltage of 1.416 (under load).
little disappointing overclock of 799core/1998shader/999memory
3DMark06: 14369

and i added a button from an old PSU to switch the mod on/off.







P.S: those RoHS compliant connections are hard to solder, couldn't melt the metal with my solder ehehe.

[3oh6]

P.S: those RoHS compliant connections are hard to solder, couldn't melt the metal with my solder ehehe.

yeah, for large PB-free joints you want a big chisel tip and a good iron that can hold 800F for the amount of time that you need the solder flowed for. otherwise you are going to get an ugly joint and it's going to be a PITA, there is just no avoiding it...but you have done not bad. for non lead free, 750F is the standard soldering temp and is usually more than enough...but nothing uses standard or AT paste anymore, it's all PB-free these days.