ATI 4850/4870 voltmod thread

NBF, I talked with my friend Jaan (some of here might know him for his exteme Vmoding skills) atm. He gave some hints how to look right place. I'll do some measurements and report back. And it can be the BD-AF IC ;)

EDIT: I tried to figure something and here are my thoughts:
http://ceemic.pri.ee/hardware/hd4850_2/hd4850_02g.JPG
First bet would be "14" marked on my pic. Resistance to GND is ~1002 ohm (~1,0k ohm). If You have time maybe You can confirm it? 20k VR should be safe. There are many good soldering points. Sadly, I don't have time to try it next 2 days...

IT WORKS :D :cool:
http://ceemic.pri.ee/hardware/hd4850_2/hd4850_mod.JPG

So I used 20k VR and Vgpu rised pretty lot (I used ATi Tray Tools to adjust Vgpu and render 3D):

Before Vmod:
1,044@ATT -> 1,209V/1,322V (2D/3D)
1,158@ATT -> 1,339V/1,328V

After Vmod:
1,044@ATT -> 1,268V/1,386V
1,158@ATT -> 1,405V/1,392V


http://ceemic.pri.ee/hardware/hd4850...850_mod01v.jpg http://ceemic.pri.ee/hardware/hd4850...850_mod03v.jpg
http://ceemic.pri.ee/hardware/hd4850...850_mod04v.jpg http://ceemic.pri.ee/hardware/hd4850...850_mod05v.jpg
:cool:

EDIT: I recommend a switch for 24/7 use, because 20k VR rised Vgpu a little bit too much and it boosts GPU temp! PWM and PCB temp even more!

Quote:

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Originally Posted by ceemic

IT WORKS :D :cool:
http://ceemic.pri.ee/hardware/hd4850_2/hd4850_mod.JPG

So I used 20k VR and Vgpu rised pretty lot (I used ATi Tray Tools to adjust Vgpu and render 3D):

Before Vmod:
1,044@ATT -> 1,209V/1,322V (2D/3D)
1,158@ATT -> 1,339V/1,328V

After Vmod:
1,044@ATT -> 1,268V/1,386V
1,158@ATT -> 1,405V/1,392V

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Awesome ceemic!!! Will try it tomorrow!

Do you have the 20kOhm VR set to max resistance in your test?

Quote:

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Originally Posted by NBF

Do you have the 20kOhm VR set to max resistance in your test?

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Max res ofcourse. I'm even thinking changing the 20k VR to 50k VR...

Btw, please measure the FB -> GND resistance and report back Your result.

Quote:

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Originally Posted by ceemic

Max res ofcourse. I'm even thinking changing the 20k VR to 50k VR...

Btw, please measure the FB -> GND resistance and report back Your result.

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I'll measure it and report back ;)

I think 50k VR will give better control. I dont have it at home so maybe I'll add a fixed 10k to a 20kVR to give some offset. :up:

20k has better (smoother) controll, but the first default jump is too big.

Quote:

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Originally Posted by ceemic

Max res ofcourse. I'm even thinking changing the 20k VR to 50k VR...

Btw, please measure the FB -> GND resistance and report back Your result.

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FB -> GND resistance @ stock card is 1004 Ohm

Mod is working good!!! :up:

Thanks ceemic :clap:

NBF, nice to know :)
I had 1002ohm FB->GND. What VR You used and how much Vgpu changed?

Quote:

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Originally Posted by ceemic

NBF, nice to know :)
I had 1002ohm FB->GND. What VR You used and how much Vgpu changed?

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Used same spot you did for soldering, ended up using 10k fixed + 10K VR, that is what I had in hand. It raised Voltages quite a bit, Reads 1.320V@idle and 1.398V@load with VR to max :rofl:

But I'm not happy with clock achieved yet, almost 1.4V and card is benchable only at 760.

I'll work on the cooling and then aim higher clocks.

NBF, my card isn't a good clocker also, ~1,55V@+10C ambient and hard to pass 900MHz :(

lol are you kidding me ? my 4850 needs 1.8V for 970Mhz lol

Quote:

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Originally Posted by Vatos_locos

lol are you kidding me ? my 4850 needs 1.8V for 970Mhz lol

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:eek: Isn't OVP somewhere@~1,6xV? :confused:
I had my friend's Sapphire reference PCB (2-phase PWM) HD4850 and it did 960+@1,57V :rolleyes:

nope no ovp for me :p: sapphire 4850 1Gb
the previous card clocked much better 1.4V for 870 but she died @ 1.5 :(

This week I'll try, what my card can do under LN2 :D

hello huys, could you be so kind and show me vmod for palit sonic 4850?)

and btw, all 1gb 4870 cards have hynix not qimonda?

Quote:

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Originally Posted by -DC-

hello huys, could you be so kind and show me vmod for palit sonic 4850?)

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Do a pic from Your card and tell what controller there is;)

Quote:

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Originally Posted by ceemic

Yes, You can use all these points:
http://ceemic.pri.ee/hardware/hd4850gs/hd4850gs_04m.jpg
I soldered over the two point marked with blue lines :)

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could you please describe what you did exactly? you´ve soldered one wire to to point above 1 of C11 and R from R34, that wire goes to one side of the 100k VR (base contact?) and the other side goes to that big joint on the other side of pcb... but what is that third wire (yellow) for coming from the VR? or is it just the insulation for the red wire?

kind regards

Quote:

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Originally Posted by ceemic

Do a pic from Your card and tell what controller there is;)

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i don't have it atm) my friend asked to help him) ok, i'll ask to make some pics

leinad78, You mean this: http://ceemic.pri.ee/hardware/hd4850gs/hd4850gs_09.jpg ? It's just insulation (thermoshrinkable cover).

thanks, i will try that at the weekend :up:

whats that brown single connector for?

leinad78, Vgpu monitoring for DMM. http://ceemic.pri.ee/hardware/hd4850gs/hd4850gs_16.jpg

so i could use that connection at the resistor to measure Vgpu against 0v?

so, done Vmod to my reference Powercolor 4850 two days ago. Runs with new bios @ 1,37V load with 825mhz 30 minutes renamed Furmark stable. Mem does 1120 Mhz without VMod yet.
May i try 1,4V to push the card to 850+? I tryed 1,41 V but the red led followed a black screen ;) - is there a volt limit on 4850? Or are the phases getting to hot? The cooler on the phases has around 40°C after 30 minutes furmark. GPU temperature shown in Furmark is 40°C / 100°F load.

I messaured 1,37 V @ 850 Mhz, Furmark load, then the driver restarted after Furmark error, system keept running. But when i messaured load again, voltage dropped about 0,03V - and with the second error in furmark, the voltage dropped 0,03 V again! This is serious. Someboy may be able to explain this "feature"...
After reboot, voltages were @ 1,37V again. So i have to reboot after every furmark error.

Thanks for help.

I think I got the worst mem clocking 4850 ever...

A Powercolor that comes with 650/950 stock clocks, card can't even do the regular 1000 on memory without artifacts. :rofl:

If you see something that looks like that.... just run as fast as you can :ROTF:
http://img511.imageshack.us/img511/4881/imagemxq5.jpg


Oh well, Ill try modding Vmem to see if gets any better.