8800GT voltage mods

[oohms]

Resistor for OVP mod:



This thread by hipro5 will tell you more:
http://www.xtremesystems.org/forums/...d.php?t=162124

[oohms]

MIGHT be the vcore solder point:



(Got info from http://xtreview.com/review164.htm )

Dinos22: What is the resistance between point 1 and ground?

Gawd this is so much more fun than studying for exams

[dinos22]

MIGHT be the vcore solder point:



(Got info from http://xtreview.com/review164.htm )

Dinos22: What is the resistance between point 1 and ground?

Gawd this is so much more fun than studying for exams

LOL i know what you mean about taking a break from studying

i used to go play golf of all things (actually just practice shots myself a looooooong time ago )

what is point 1 that you refer to

[oohms]

what is point 1 that you refer to

The circled point in the last pic (connected to vsense)

[metro.cl]

The circled point in the last pic (connected to vsense)

015 from what i get.

Pin 1 to ground

[largon]

MIGHT be the vcore solder point:



(Got info from http://xtreview.com/review164.htm )

Dinos22: What is the resistance between point 1 and ground?

^This spot-to-GND is essentially the same as spot2/spot3-to-spot4 in this pic:


I'm pretty sure we're talking about the right soldering spot for the vGPU mod... But here's a safer (it's not a populted SMD solderpad) and much easier soldering point:

[largon]

11Ω (or 15Ω?) between vSense pin and ground is a horribly low resistance. I was expecting something around 45Ω since G80GTS/GTX which measures to 35Ω output 1.28v, and since the GT has lower vGPU thus the sense resistance should be higher than those on GTS/GTX as all use the same PWM IC. <20Ω is very low and IMO somwhat suspicious...

If someone is willing to be a guinea pig then I would suggest soldering a 500Ω multiturn VR between this point and ground. Before soldering measure the resistance between soldering points (should be ~15Ω), set VR at max resistance (500Ω), solder the VR, measure resistance between soldering points (should be ~14.5Ω, if much less don't turn the card on) tune down for more vGPU.

[metro.cl]

11Ω (or 15Ω?) between vSense pin and ground is a horribly low resistance. I was expecting something around 45Ω since G80GTS/GTX which measures to 35Ω output 1.28v, and since the GT has lower vGPU thus the sense resistance should be higher than those on GTS/GTX as all use the same PWM IC. <20Ω is very low and IMO somwhat suspicious...

If someone is willing to be a guinea pig then I would suggest soldering a 500Ω multiturn VR between this point and ground. Before soldering measure the resistance between soldering points (should be ~15Ω), set VR at max resistance (500Ω), solder the VR, measure resistance between soldering points (should be ~14.5Ω, if much less don't turn the card on) tune down for more vGPU.

Damn i found a couple of VR but i think they are not good for the mod i got a 50kΩ and a 10kΩ VR here.

i'll have to find 500Ω VR but i think it will be hard

[metro.cl]

^This spot-to-GND is essentially the same as spot2-to-spot4 in this pic:


I'm pretty sure we're talking about the right soldering spot for the vGPU mod... But here's a safer (it's not a populted SMD solderpad) and much easier soldering point:

that one to ground? what VR value should i get? the space is pretty small and my soldering skills bad but i'll give it a try.

There is no way for a vGPU pencil mod?

[wittekakker]

hows your results?

Unfortunately this card aint mine, just did a quick research so to please the OC-community. No results, but I can tell you that I could increase to 1,2VGPU. Anyway, XS counts enough people owning such card, it will not take too long before those cards are running at 1GHz I suppose

Sorry to ask but which of both legs is Vsense+? could you upload a picture of the modded card.

Didn't picture it, you will have to take me on my word here
Vsen+ is the pin marked below:

[2bb1]

Hey! Tried the volt-mod on my 8800GT today. But first, could you look at the picture added below; what is that thing? A capacitor?

[largon]

2bb1,
You mean this one? It's a resistor.


Why?

[oohms]

Hey guys, im going to need some help with this one. Basically i found a number of mosfets on the board whose output voltage i can adjust. But 3 voltages are unknown to me:

red 1.10v Vcore
brown 2.00v Vdimm
yellow 1.79v Tiny mosfet
blue 5.05v Large mosfet (Looks like 5V supply)
green 2.44v Large mosfet, near front of card
gray 1.18v Large mosfet

[2bb1]

2bb1,
You mean this one? It's a resistor.


Why?

Yes that one!
It fell off while I were modding. So I "cancelled" the vmod to check if the card were still working; and it does. How can this be if I've removed a resistor? Can it be this way, or should i "mount" it back on?

[oohms]

Ok i found out a few things today.. (went and downloaded the datasheet for the samsung ram it uses)

- Vdd = Vddq (Damn cheapskates )

- Vref is controlled by a voltage dividor as such:


Now im just clarifying, i reduce the resistor between Vref and Vdd to increase Vref right?

(The only bad thing about this is that each chip has 2 separate Vref points, so 16 modifications in total )

edit: as it is, that will provide Vref = 51&#37; of Vddq, instead of 70% of Vddq

[jason4207]

Ok i found out a few things today.. (went and downloaded the datasheet for the samsung ram it uses)

- Vdd = Vddq (Damn cheapskates )

- Vref is controlled by a voltage dividor as such:


Now im just clarifying, i reduce the resistor between Vref and Vdd to increase Vref right?

(The only bad thing about this is that each chip has 2 separate Vref points, so 16 modifications in total )

edit: as it is, that will provide Vref = 51% of Vddq, instead of 70% of Vddq

Are you trying to isolate the memory voltage from the memory controller voltage? I was told that wasn't possible, but if you get it working I'm very interested to try it!

[2bb1]

Yes that one!
It fell off while I were modding. So I "cancelled" the vmod to check if the card were still working; and it does. How can this be if I've removed a resistor? Can it be this way, or should i "mount" it back on?

Can anyone tell me if it's OK that the resistor is gone?

[os008]

Can anyone tell me if it's OK that the resistor is gone?

I think it depends, the card might work fine, but there might be a voltage increase because of removing that resistor, or a decreased functionality that won't appear till you do something specific, or just a general instability!

You should consider replacing it though. Someone here could give you better advice.