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GIGABYTE Radeon HD 7870 Windforce3 Voltage Mod?

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N0ble

Registered
Joined
Aug 13, 2012
Can anyone help or point me in the right direction?

I have been searching Google to no avail.

I would like to establish where to solder for a voltage mod on GIGABYTE Radeon HD 7870 Windforce3. For DRAM, PLL and VCore.

I actually have a Rampage extreme IV and would like to use the Hotwire leads if possible, need 1 lead for sense and the other for voltage increase, failing this just apoint in the right direction of where to solder resistors would be of benifit.

Pictures of the card here.

http://www.kitguru.net/components/gr...indforce-3x/3/

Thanks,
Lee
 
It's more a question of whether you want to remove and replace those tiny resistors. If so, I'll try to walk you through the process.
There isn't a voltmod that doesn't require removing them and replacing them though.

EDIT:
Unless of course that page IS the 7870 windforce card, in which case it has a guide.

2.EDIT:
Looks like the GBT card is probably close enough.
Measure the resistance between the vGPU mod point and ground, if it's somewhere in the 3ohm to 8ohm range, that mod will work.
Measure the vMem mod point to GND as well, should be 3k to 8k.

Voltage read points are fairly simple. For the memory you'll find a larger surface mount cap under each ram chip. One end of it is connected to ground, the other is connected to vDDR.

vPLL is likely the little square chip between the inductors on the PCIe power plug end of the card. vPLL mods are generally only useful for moving the coldbug on the card, if you're on air or water cooling I wouldn't worry about it.
 
Last edited:
Ok cool. I dont mind, i will remove them if need be and i really do appreciate your time and help. Thank-you so much.

I shall check this when i get home from work and report back.
 
Just a quick one, if the resistance is between 3ohm to 8ohm range, does that mean that i can use Rampage Extreme VGA Hotwire with it?

Would it be as simple as soldering the red wire to the reference point and the blakc to a read point, or would it require further resistors?
 
I believe that for hotwire you need a higher resistance, you'll probably need to swap the resistor for a higher resistance one. This will also raise the default voltage a bit.
 
Ah ok. Could I just place an inline resistor on the wire the bump it up a little? Where would I start to understand if I did need higher resistance on the hot wire?
 
I would guess at measuring the resistance on the line from the board to ground with it powered on at default settings?
 
Measure the resistance from where they show the wire being soldered to ground, with the board out of the computer.

You can't measure resistance with the thing powered on due to how multimeters measure resistance.
For hotwire I think you'll need at least 200ohms, Shammy recommended ~500ohms for the same controller on a 7970.
 
Excellent. Thanks. Not long before I'm home. So will take initial readings of vcore point and report back.
 
Completed a read out.

On R681 which i believe is the correct one to look at?
It's 3.2 Ohms.

Below is the reference picture taking it from what looks like R681?
p1270740580x457.jpg



And below is where i took my reading point from which im hoping is correct?
20120813183910.jpg



If i attempted to reaad the Hotwire Vcore point to ground with the system powered off it did not register any reading.
I will add that the board was still in the case, but the fact its reading nothing... then there is no point in even removing it?

And finally, for reference later on when i finally do the memory voltage mod do i take voltage reading from the cap circled in yellow or the points next to it circled in pink?

20120813184413.jpg
 
Did you test the mod point for resistance? Not voltage, mind you. There should be a few ohms, it's possible that there aren't though.
Also test the same end of R682 next to it. One of those is vsense+ the other is vsense-

The pads or the caps should work for the memory read point. I'd probably use the caps.
 
Did you test the mod point for resistance? Not voltage, mind you. There should be a few ohms, it's possible that there aren't though.
Also test the same end of R682 next to it. One of those is vsense+ the other is vsense-

The pads or the caps should work for the memory read point. I'd probably use the caps.

Yeh, i did.
The vcore modpoint is R681 @ 3.2 Ohms.
R682 is 1.3 Ohms.

Below is the reference picture of the vcore mod.
p1270694580x355.jpg


I think i may leave the Hotwire mod and just go for resistor to make things less confusing.

I may still wire up the voltage read out points to the hotwire points though, that way i can at least always see what voltage im running from the pc screen without need of multimeter, every time i want to check.
 
I think that's what I would do, much easier than removing and replacing resistors and such.
 
I think that's what I would do, much easier than removing and replacing resistors and such.

Cool, so for the voltage read points it should be as simple as soldering a wire to the point and then connecting to the sense point on my board, no need for any additional resistors or anything?

So wiring up a 50 Ohm trimpot to R681 should work based on it being 3.2 Ohm at present?

Does it matter which side of the resistor i wire to and im guessing i would start off with it set at 50 Ohms and then work my down until the voltage increases enough?
 
Doesn't matter which side you use, and yes start with it set for 50 ohms between whatever end wire you use and the middle wire you use.

Personally I like to use the rear wire and the middle wire so that the voltage is like a water faucet. Clockwise means less voltage (more resistance) and counter-clockwise means more voltage (less resistance).

Make 100% sure you have it set for 50 ohms before you fire the card up, if it's at zero you're in for trouble.

I like to add a couple header pins for a jumper to enable/disable the mod as well.
 
Sweet, so two things now.

For VCore read, which point do i use on the board?

and my second issue, is that i cannot seem to find any 3296w 50 ohm trimpots here in the UK, what alternatives could i use?

Thanks again.
 
Any trimpot with 10 turns or more and 50ohms should work. If you want to be extra super safe you can match the wattage of the 3296w. I doubt you'll need to though.
 
Cool.

I shall try and find some...

It's the middle resistor so a little more difficult to solder to it, any tips?

Also, any idea where i can take a read for Vcore voltage from?
 
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