7900GT over voltage protection?

[***Deimos***]

So this is correct right (just asking to be sure)? to get 1.5V

yup.

Belarnion, that looks right.
However, personally, I would not do it that way. The pull up resistor for ~+5V , will now be between 5V and ground, and perhaps too much current for it.. ie burn it out. Perhaps we should wait for the experts to confirm.

Majestik.. yes you can install dip switch. But, to make full use of it, you would need to solder so many wires, one for each of the vid pins. It would be really cool though. You could just toggle whatever setting you want. If I had a 7900GT and the necessary tools (I dont even have proper soldering equipment for such miniscule stuff), I would definetly install a dip switch.

[TimeOut]

Where are the pull up resistors? Can we have a pic of them?

[s e t h]

ok wait - so pin22 and pin32 are 0 by default (connected to ground)
therefor does this picture make sence?
conductive paint would be easy to apply and easy to remove again
i prefer non solder mods for short bench sessions

then with a nice zalman900-cu we get a nice cool core at up to 1.55vgpu.
and if you want to throw warranty away you can remove the resistor and start at 1.5vgpu default
i see a gtx killer minus the fancy ram

[TimeOut]

I




BUT: If Pin 32 and pin 22 is *already* '0', why not just connect
Only pin 32 to pin 30 and 31 to get 1,350V or
Only pin 22 to pin 21 to get 1,4V or
pin 32 to pin 30 and 31 AND pin 22 to pin 21 to get 1,55V

Would that work?

Depends of what is '0' in this case. If pin #32 (and pin #22) of the ISL6568 are connected directly to ground (hardwire), then your idea works.

But if pin #32 (and #22) of the ISL6568 are connected to another chip and that chip sets the logic "0" on those pins, then there can be a big current going into pin #32 if you connect pins #30 and #31 to pin #32. It all depens of how much is VCC (pin #4) and what pull up resistors those pins have.

I'm assuming that the chip that is connected to the ISL6568 has open collector outputs. If we can figure out where are the pull up resistors and how much is VCC (pin #4), I can tell if it is safe or not to connect between pins.

It's easy to know if the pins #32 and #22 of the ISL6568 are hardwired to ground. With the card in your hands, measure the resistance between pin #32 and ground.

My 7900GT will arrive next week, so I can not do the test myself. I can only research looking at the pictures and using what people say here.

[s e t h]

ok but someone could measure resistence between pin32 and ground. if there is none the mod is good?
same for pin22?

not my idea

[TimeOut]

ok but someone could measure resistence between pin32 and ground. if there is none the mod is good?
same for pin22?

not my idea

Correct. The resitence between pin #32 and ground and between pin #22 and ground should be zero.
If not, means that there is a Chip controlling those pins. If this is the case, I would connect between pins ONLY if the pins connected together can be also connected directly to ground.

[***Deimos***]

Depends of what is '0' in this case. If pin #32 (and pin #22) of the ISL6568 are connected directly to ground (hardwire), then your idea works.

But if pin #32 (and #22) of the ISL6568 are connected to another chip and that chip sets the logic "0" on those pins, then there can be a big current going into pin #32 if you connect pins #30 and #31 to pin #32. It all depens of how much is VCC (pin #4) and what pull up resistors those pins have.

I'm assuming that the chip that is connected to the ISL6568 has open collector outputs. If we can figure out where are the pull up resistors and how much is VCC (pin #4), I can tell if it is safe or not to connect between pins.

It's easy to know if the pins #32 and #22 of the ISL6568 are hardwired to ground. With the card in your hands, measure the resistance between pin #32 and ground.

My 7900GT will arrive next week, so I can not do the test myself. I can only research looking at the pictures and using what people say here.

thanks for clearing up what I guess I was trying to say about tying the pins together and pull up resistors...
thanks

Offhand, do you know if one of the solder pads for nearby capacitor or some other solder pad, via etc, are good easy "ground"?

[cronic]

great work guys i did the .5v and .1v mod to ground and it works like a champ. soldering the .2v mod is a little to tiny for me. i am awaiting feedback on an easier way to do the .2v mod. thanks again guys for your AWESOME work with this mod.

[Mysterfix]

great work guys i did the .5v and .1v mod to ground and it works like a champ. soldering the .2v mod is a little to tiny for me. i am awaiting feedback on an easier way to do the .2v mod. thanks again guys for your AWESOME work with this mod.

I been watching this thread and the one over at VR-zone since you first did your mods so please give us an update on your gpu scaling with the new voltage.

My 7900GT is due to be ordered very soon so I'm collecting all the info I can until then.

Keep up the good work guys!

[cronic]

I been watching this thread and the one over at VR-zone since you first did your mods so please give us an update on your gpu scaling with the new voltage.

My 7900GT is due to be ordered very soon so I'm collecting all the info I can until then.

Keep up the good work guys!

running at 655 / 1820 @1.368v at desktop and 1.377v in 3d and scored 15858

which isn't to bad, hopefully i can add the extra .2v very soon and smash on through 16k
i really like the idea of a dip switch...........

[LardArse]

Just tested, the solder pads there work. Didnt dare run too long at 1.7v with the stock cooler until I change it to a better one.

[Fhqwhgads6680]

nice work guys!!! Just 2 days ago it was still a mystery!! to all you guys!! Mine come in this weekend and im gonna give it a shot. This'll be my first Hardmod...So where's the best place to get the VR for the hard mod?

Great work!

Brandon J

[aicjofs]

I'm gettting

0 ohms to ground on pin 32

5Meg ohms to ground on pin 22

judging by picture above if you don't remove the resistor you would take the "D511" point to ground for 1.4v? "D511" is same as pin 21.

[Mysterfix]

Sweet! I can't waite to get my new toy and join in on all this fun! My 7800's no slouch but those 7900GT's are some real winners @ $299, especially when you give em a little more juice!

[afireinside]

Just tested, the solder pads there work. Didnt dare run too long at 1.7v with the stock cooler until I change it to a better one.

Great work sham! That's sooooo easy. I'm kicking my self here because all the XFX XXX's are sold out

[s e t h]

someone please check pin20 to ground? maybe it's 0

[***Deimos***]

running at 655 / 1820 @1.368v at desktop and 1.377v in 3d and scored 15858

which isn't to bad, hopefully i can add the extra .2v very soon and smash on through 16k
i really like the idea of a dip switch...........

wow, great results. It seems 1.35V is sufficient to get GTX speeds

Now, please be clear: did you connect pin 30 & 31 to pin 32, like in your diagram (ie tie all 3 together)?
Or did you use pin8 on the IC for ground?

Also please provide your opinions on what you feel is the easiest way to do this. I sense dozens of folks here who are scared to touch a soldering iron, but want to give this a go.

[nn_step]

Very nice mod, I'll be sure to do it when I get my card in a couple days

[t024484]

I'm afraid it won't be much easier...

BUT: If Pin 32 and pin 22 is *already* '0', why not just connect
Only pin 32 to pin 30 and 31 to get 1,350V or
Only pin 22 to pin 21 to get 1,4V or
pin 32 to pin 30 and 31 AND pin 22 to pin 21 to get 1,55V

Would that work?

Yes, this will work. Without changing the Resistor, you will have 1.55Volt.
Do not worry about burning pull up resistors as somebody suggested, these pull up resistors are very large in value.
To be more specific, the internal pull up resistors are in fact internal current sources, supplying 40UA ( 40exp-6 Amp) of current wen the input is connected to ground.

[Pyr0]

Yes, this will work. Without changing the Resistor, you will have 1.55Volt.
Do not worry about burning pull up resistors as somebody suggested, these pull up resistors are very large in value.

so there's no need to remove any resistors at all?
all that's needed is to bridge those contacts for up to 1.55v?

i'm stilll waiting for my xfx card, but if the mod is really this easy i might actually try my first hardmod

[t024484]

so there's no need to remove any resistors at all?
all that's needed is to bridge those contacts for up to 1.55v?

i'm stilll waiting for my xfx card, but if the mod is really this easy i might actually try my first hardmod

Yes, that's all there is.
On the other hand, if you are not a skilled solderer, you can, as an alternative, solder the two larger points (more on on the edge of the board) to ground, that LardArse found to be in direct connection with point A (+0.2Volt) and B (+0.1 Volt) . That will give you up to 1.5 Volt

[Pyr0]

thanks t024484, and of course everybody who all helped defeat the OVP

[t024484]

LardArse,
Why do you think that the two resistors indicated in some picture from you, remove the current limit. Where are these resistors connected to?
According to the chip supplier the current limit is set with a resistor between point 10 and point 11.
This is just one resistor instead of two.
On the other hand, there is no mentioning until now if the current limit comes into action at all with the higher Vgpu.
I would have expected that to happen with 1.5Volt and 750 Mhz.

[***Deimos***]

Yes, that's all there is.
On the other hand, if you are not a skilled solderer, you can, as an alternative, solder the two larger points (more on on the edge of the board) to ground, that LardArse found to be in direct connection with point A (+0.2Volt) and B (+0.1 Volt) . That will give you up to 1.5 Volt

On his diagram he has 1.6V and 1.7V. I assume thats because he's using the VRM9 codes (aka replace resitor with 50K). Also, since I dont have a 7900GT (yet), could we get a better zoom shot of that area... where exactly is that in relation to the IC pic of the front?

thanks t024484, and of course everybody who all helped defeat the OVP

I dont think Cronic did the over-current protection, and he's well past 650Mhz. I dont think its needed up to 700Mhz.. not sure when? Not defeated over-volt protection really, since cant disable it.. just different way of over-volt mod... now in 2006 its digital :p

[96redformula]

I give you all a big applause . I am in AWE right now . I wish I could do the modification myself. My only soldering experince was with the ASRock 939 Dual and a huge solder gun. Ended up with a huge drop on the spot, luckily I pulled the solder gun up on time. It looked like a waterdrop about to splash on the board .