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Radeon HD 4870 Voltmods

erocker

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#2
Wow, that's a tiny place to soldier for the VDDC! I better not have any caffiene that day! Thanks so much W1zzard!:toast:
 
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#3
holy shizzlet! Volt mod's already! :rockout::rockout: :respect::respect:
 

Mmatao

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#4
test of shappire 4879 gpu vmod, fan to 42% stock cooler.
room to 27º C

test passing atitool
without vmod 76º C 1.26v max gpu 770mhz
with vmod resistance 100 oms 79º C 1.28v max gpu 820mhz
with vmod resistance 50 oms 82º C 1,295v max gpu 825 mhz

the best configuration is 100 oms to stock cooler.

I do not understand mvddc and mvddq, as is the one that there is to fit?
 
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W1zzard

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#5
Wow, that's a tiny place to soldier for the VDDC! I better not have any caffiene that day! Thanks so much W1zzard!:toast:
unfortunately there is no better place to solder. on the other side there may be some spots but with the cooler on top its kinda difficult to put wires there.
 
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#6
Could somebody per chance check if AMD GPU Tool really changes voltages? I don't have a multimeter and have no way to check... please somebody? :)
 

W1zzard

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#7
vddc reading spot fixed, the picture in the article now points to the correct location
 

chron

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#8
I thought these cards had "dynamic voltage control" so you wouldn't have to do all this?
 

W1zzard

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#9
yes you can change up like 0.1v in software and down about 0.3v .. in 4 steps. but at this time there is no software to control voltages, other than modding the bios
 

Haste

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#10
yes you can change up like 0.1v in software and down about 0.3v .. in 4 steps.
Hi. What do you mean with the "in 4 steps" ? I've modded the 4870 BIOS using RBE 1.11 but it doesn't seem to have any effect on voltages. I tried increasing it from 1.263 to 1.276 and 1.302 but without success. The vcore was not changed. So is there another way to up the GPU voltage by 0.1v? Thanks.
 

W1zzard

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#11
the card can only select one voltage out of four. so there is something like 1.0, 1.1, 1.2 and 1.3. the card has to pick one, ther is nothing like 1.15 possible in this example.
i dont know the actual voltages that are implemented.

did you change the right profile? i think a 0.1 increase should be possible
 

Haste

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#12
Yes, I think so. In the RBE it has high profiles at 3 and 9. 4 to 6 are UVD profiles. I've changed the 3 and 9, both to the same voltage I mentioned before. Now I have it at 1.363 (exactly 0.1v above normal) but no success again. Even people from XS forum didn't have any luck with BIOS voltage mod so i feel a bit skeptical about it. I would appreciate any help with the mod. I'm willing to try almost anything... have my old PCI card ready if necessary :)
 
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#13
I didn't find a 50 ohm pot locally. Does a 100 ohm 15 turn one would be precise enough to reach high voltages (1.5-1.6).
Or a 20 Ohm one would be better suited ( i have both ).
 

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#14
I'd recommend fixed 20ohm resistor and I really hope that you have water cooling at least. 20ohm ~ 1.5-1.6v. And be careful, that vddc solder point is really tiny.
 
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#15
With a tiny spot like this could i put some hot glue on it after the wire is soldered to ensure it doesnt break?
 
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#16
In a what I consider related story: I stumbled upon a forum with a post by a guy who made some images with a thermal camera of his 4870, and you can see some interesting result from the voltage converter area.
Translated link:
http://translate.google.com/transla...hread.php?t=510938&hl=en&ie=UTF8&sl=d e&tl=en

Note how he writes the GPU-Z values reported above the pictures, so keep in mind that those sensors on the board only tell so much.
 
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#17
From my testing doing the GPU Vmod with fixed resistors,

33 Ohm=1.35v idle 1.37v load

27 Ohm=1.37v idle 1.39v load

22 Ohm=1.385v idle 1.405v load
 

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#18
Anyone know how much resistance is needed to raise the memory voltage to 1.6v ?
 
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#19
anyone have a picture of the actual mod yet? I wanna see some working mods before I decide to take the dive.
 

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#21
hi, I would like to show you my card. its pcb is slightly different from the one in the vmod guide, the vgpu soldering point is covered and there are a few more transistors around. it's a club3D 4870 oc'ed edition.
I would like to know if the soldering points are the same (probably yes).
sorry for my bad english, I'm Italian :D
 

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#22
I'm looking around & I heard about some pencil VDDC mod on 4870...




Did somebody try them ?
 
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#24
Guys, I have a PowerColor 4870, but with more than 825 in the Core she presents a strange behavior, I have BSOD.

How to resolve?

BIOS OCX 1.276v
 
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#25
RMA - sounds like U got a bad card.

I have the same card, I get 850/1100 stable - everything maxed out, w/ a Scythe Musashi cooler. http://www.scythe-usa.com/product/vga/002/scvms1000_detail.html Runs great - no problems at all.

I actually have two of these cards, same story on both. Crossfire doesn't scale well at all on my system. Card was unstable in crossfire, OC'd or stock. Running a single card - excellent performance! Maybe my next rig (and later drivers) will better support them in crossfire.

Running it w/ a QX9650 OC'd to 4.2Ghz.