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Non-Ref 9800GTX+ Vmod

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ChanceCoats123

d20 in a jacket
Joined
Feb 1, 2009
Location
Illinois
I'd like to get this thread going so once I get everything I need to do the mod (hopefully), I will be able to get it going and then freeze the crap out of this card. :)

I have some macro shots that are as good of quality as I can get them, but still aren't very good. I did take the time to look up the data sheet and some other vmod threads, and we might have issues...

Here is the data sheet.

Here is the macro shot:

Macroofvoltmod-1_zps5d63ac6b.jpg

From the research I've done, and my mediocre data sheet reading skills, it seems the voltage output (vtt) is through a set of 680 ohm resistors in parallel. I'm assuming I could still do a voltmod, but it definitely won't be adjustable because I would have to solder a VR to each of those resistors. So I could grab some smaller resistors and further decrease the resistance to increase the voltage supplied.

But that's just my first idea after seeing the data sheet. The real world way around it might be different.
 

Bobnova

Senior Member
Joined
May 10, 2009
Find the resistor connected to the VS+ pin, measure its resistance to ground (from the controller side of the resistor).
If it's above ~3ohms, continue like a normal voltmod pretending it's the FB pin. (so a trimmer 15-20x the current resistance to ground, connected to ground)
If it's less than that, you're in for some entertainment. I'll help you with that, too.

To disable OCP, connect the ILIM pin directly to the ROSC pin (you don't have to solder to the IC, you just need to bypass the resistor that currently connects the two pins and sets the OCP threshold).

That'll do it, no OVP as it isn't sensing the "high" voltage, no OCP because you disabled it.
 
OP
ChanceCoats123

ChanceCoats123

d20 in a jacket
Joined
Feb 1, 2009
Location
Illinois
According to the data sheet, that first component is a cap (which makes sense because of the color). Controller side to ground on that cap is 15 ohms. Then I followed the trace to what I believe is a resistor (black body), and 15 ohms to ground on that as well.

Trimmed resistances.jpg
 

Bobnova

Senior Member
Joined
May 10, 2009
The datasheet layout and the board layout may be very different, the datasheet shows an example layout, manufacturers are free to play with it!

Slap a 500ohm VR from either of those points to ground and see what happens.
Make sure you're modding VS+ and not VS-.
 

Bobnova

Senior Member
Joined
May 10, 2009
Yup that'll work, I think I'd do it from the VS+ to a different ground point though. Leave the cap in place though, donno if the scribbles mean anything but don't remove either part. The cap is needed for smoothitude, the resistor is needed in case you want OCP back in the future.

Measure the resistance across that cap on the VS+/VS- lines, the resistance across it may be higher. As long as it's less than ~20ohms the 500ohm trimmer across it will work fine.
 
OP
ChanceCoats123

ChanceCoats123

d20 in a jacket
Joined
Feb 1, 2009
Location
Illinois
21.5 ohms across that cap. I'll leave those components in place, and I'll ground to one of the pins in the 6-pin connector (or is that a no-no?) just because it's a nice big ground pad.
 

Bobnova

Senior Member
Joined
May 10, 2009
You can try, good luck though. Those have massive amounts of copper attached and are very hard to solder to.

21.5 ohms is fine to solder directly across the little cap. That'd be nice and clean, it's what I'd do.
Admittedly I tend to set challenges for myself when it isn't an obscure setup. (My favorite is the "no wires" challenge, vmod with just cut off resistor legs for transit. Obviously the controller needs to be close by)
 

Johan45

Benching Team Leader Super Moderator
Joined
Dec 19, 2012
Did this work? I have the same card it looks like and want to get more powa from it.
 

QuickFast

Member
Joined
Dec 21, 2011
Location
Nerwport,NC
^^^I see you been benching this card did you wined up volt modding the card ? looking a the pic's looks like there's a easier solder point for the gpu if you didn't volt mod and done benching the card let me know if you wan't to give it a go
 

QuickFast

Member
Joined
Dec 21, 2011
Location
Nerwport,NC
:D please post pic's of your card-Is your 3870x2 working, I Am working on VID MOD's on my card could send it to you if all works out- got home made pots for it to- luv to see over 1000 on the core :) (FOR TEAM CUP)
 

Johan45

Benching Team Leader Super Moderator
Joined
Dec 19, 2012
Funny thing I tried it in the z170 and it's working but weird lines and shett. Might be able to fix it with a BIOS maybe not sure but it's at least beeter than black screen like it was on the formula. I'm going to pull the backplate off. I think there should be pads on this one and there isn't maybe ground ing something/. Hopefully I can ressurect it. But I can't get an AM2 going. Gonna have to break down and get another one.
 

QuickFast

Member
Joined
Dec 21, 2011
Location
Nerwport,NC
thought it might work on a new platform- replace TIM could be dried out and use bottom dvi been a couple of years I booted up this card (just did on a X38 chipset)If you what I could upload my BIOS's but you should have no problem finding them online
 

Johan45

Benching Team Leader Super Moderator
Joined
Dec 19, 2012
Does yours have a backplate and is there padding on it? Mine has a plate with no pads under it and it appears to be touching things. Maybe I'm getting some interference?
 
Last edited:

Johan45

Benching Team Leader Super Moderator
Joined
Dec 19, 2012
I'll put some on and see if it helps. What I was seeing is usually an effed up BIOS or ram problem so maybe they were hot but shouldn't be. It can't hurt anyway.
 

QuickFast

Member
Joined
Dec 21, 2011
Location
Nerwport,NC
these card have voltage control with software maybe try undervolting the card to test if core is toast or not, I know I have cards that will start artifacting if I start put any volts to the core
 

Johan45

Benching Team Leader Super Moderator
Joined
Dec 19, 2012
Got the card apart 9800GTX+ and I don't think it's the one I linked either. Have to get pics tomorrow too dark and they're crap right now.