GF4 Ti4200 Voltage Mod

[asw7576]

Has anyone in this forum knows electronics or has done voltage modification on GF4 Ti4200 cards?

I have done some research:

http://www.maximumoc.com/guides/4200voltmod.html

But I am not sure with credibility of the above thread ( I disagree with its Memory Voltage Modification. I believe the Voltage of Input/Output Memory Buffers would go beyond specs when increasing DDR voltage at the same time).

Look here for what I am talking about:

http://www.xbitlabs.com/video/visiontek-gf4ti4400/

This xbitlabs guy is using a diode to lower input/output memory voltage buffers when increasing the DDR voltage at the same time. Unfortunately the card modified is GF4 Ti4400, which is different circuits than Ti4200 cards.

I have test it using 1000 ohm resistors with my GF4 Ti4200: One resistor for GPU, and the other one for Memory. The results: It works on GPU, it is running 320MHz. But nothing happens for the DDR speed. It still stucks at 550Mhz speed. Damn.....

Right now, I am running the card at 320 GPU / 550 Mem, and 3Dmark2002SE score is fluctuating from 11,353 to 11,495 (????)

Any comments?
Any voltage modification would like to share?

[asw7576]

Here is picture on modified Semtech CS1102 DC/DC voltage distribution IC:

http://www.semtech.com/pdf/sc1102.pdf


http://www.maximumoc.com/img/hardware/abit_4200/back_labeled.jpg

[asw7576]

Ok... I have done modification again on my Ti4200 card. This is the result: Adding a 680 ohm resistor for GPU is working fine, up to 335MHz. And adding another resistor ( I tried 680 ohm or 1000 ohm ) for Memory is nothing but some ripples on monitor screen.

So, the article in maximumoc.com: http://www.maximumoc.com/guides/4200voltmod.html
is B.S for memory modification . The modification on memory speed is not working because it increases the voltage of input/output memory buffers and DDR voltage at the same time. It needs diode to lower voltage going to memory's buffers circuits.
I don't know where to put the diode at the moment. I will let everyone know where to put a diode on Ti4200 cards.