Asus 8400GS vmod

[GOESA]

Hey XS.org

I need your help on the soldering points on this card asus 8400gs I have added a picture, could not get a better picture. but hope you can help me.

the chip uses this IC on the card:

APW7068
AJ5CM



/Grau

[GOESA]

Got a better picture, alittlebit better.

Any help would be great

/Grau

[Zeus]

I reckon pin 4 is feedback (FB) and pin 7 is ground.

Measure ressistance between pin 4 an pin 7, multiply by 20 and put a VR of this value onto pin 4 and pin 7.

For example, if resistance between pin 4 and pin 7 is 500 ohm, multiply this value by 20, 500x20=10.000 so use a 10K VR.


Don't quote me on this as i'm not 100% sure FB actually means feed back but i have a strong feeling it does.

For Voltage reading point, put the card in your system, turn system on and measure at the resistors that are close to the thumbscrew that hold the cooler or at the pins of the caps that poke through the pcb, you should be able to measure Vgpu there somewhere. (do this prior to the Vmod)

Done at your own risk.

[largon]

Can't really use those pics for anything...

Anyways, the mod is:
Pin 4 of APW7068 to ground via a VR with a maximum resistance of ~20× the measured resistance from pin 4 to ground. Lower resistance to increase voltage.

edit:
Zeus was faster.

edit2:
GOESA,
I bet there's a macro-mode (marked with a flower symbol) in you Powershot A60...

edit3:
What comes to the vGPU measuring point...
These appear to be the legs of a copper coil ->

Both of those red spots are good vGPU measuring points.

[GOESA]

Thx found the flower

Took one without flash and one with, does this help any or just say where to take the picture,

would like to get for the vmem aswell.

/Grau

[GOESA]

So can you point out where to mod exactly?

/Grau

[STEvil]

Here's a macro from my Canon SX100IS... dont really need it now but whatever helps.. in case we need overcurrent fixed as well I guess

The pin with the dot by it will be pin 1. Go left counter-clockwise to count.. so 4 is the center pin and 7 is far left, all along the "top" of the IC in my picture.

Check that 7 is actually ground before doing the mod though just in case they printed the IC's upside down or something rediculous.

[STEvil]

I measured 600 ohms from pin 4 to 7. Gonna see if I can find where I stashed all my VR's...

edit - 10K VR is what you will want to start with.

[oohms]

Are there any other vreg chips on the front of the card? If not, pin 6 - pin 7 could be a point for Vmem.

[STEvil]

I can confirm a 10K VR from 4 to 7 is vGPU... running 1.4v now

[STEvil]

6-7 doesnt seem to be vmem, took a vr down to 3K on it with no change in vmem, circuit resistance was 780 ohms with no VR in it.

That other IC labeled "74D7KHK / ACT08" might control vmem....

edit - Dont think its the ACT08 IC... hmm.

[oohms]

Originally Posted by STEvil

That other IC labeled "74D7KHK / ACT08" might control vmem....

No thats a quad input AND gate. We need some more photos methinks

[STEvil]

The only other IC is an 8-legged one on the front which hides under the heatsink and looks more like a driver IC like what you'd see paired with some mosfets.. i'm too lazy to take the vf700-cu off right now lol (midnight).

edit

We might be looking in the completely wrong spot:

[STEvil]

ok, you win... here's the front IC.

Looks like it could control vmem I guess.

edit

here's another on the back..... need to get a better shot so the text can be read

[oohms]

That first one is the bios chip and the second one is a chip related to HDCP output.

It could be something like what the xfx card uses, but they are a pain in the ass to locate because there is a lot of multimeter probing involved

[Zeus]

I hope this helps:

[GOESA]

Thx guys! really nice,

how about the vmem mod?

/Grau

[GOESA]

Hi found something

http://forums.vr-zone.com/showpost.p...0&postcount=17

According to this thread the one that controls the vmem is a chip called 431L which has 3 legs, I found that one on my card, but on the front of the card instead? has this anything to do with the vmem mod?

/Grau

[xoqolatl]

This IC is "1.24V Adjustable Shunt Regulator"
when you look at it so that two legs are on the bottom, left leg is Vref. Decrease resistance between Vref and ground to increase output voltage.

[GOESA]

okay but is it for the vmem you think?

/Grau

[xoqolatl]

Well it's definitely not for GPU Of all things on vid card that might need a voltage regulator like that, only memory comes to my mind.

[GOESA]

thx man only one way to find out now

/Grau

[STEvil]

I think its 431L, 10k to ground from the leg closest to the wires that go to the VGA connector should do the trick.

I wont be able to test tonight. Will try to do it tomarrow.

EDIT

I went and tested anyways lol.....

Yup, 431L to ground with 10K VR = VMEM mod. Quick test at 2.15v then I gotta run 'cause i'm late now lol

edit

486mhz @ 2.2v so far. 493 caused a crash.

Gotta find a datasheet for the Qiumonda 2.5ns chips..

[GOESA]

Good for you STEvil! Damn, then they scale well enough with volts! Yes!

So could you point out where exactly you soldered? the leg closest to the VGA connector, to ground? which one is ground?

/Grau

[STEvil]

Just used a ground on the back of the card that holds the backplate bracket thing on.

Edit

added vGPU just so its all finalized.