ATI 3850/3870 Voltmod thread

Updated:

Tested by multiple users and the mods work fine.

Mods are carried out at your own risk. I will not take responsibility for any voltmods gone wrong. No-ones forcing you to mod your cards and invalidate your warranties.

http://img119.imageshack.us/img119/8...inalic3.th.jpg

http://img504.imageshack.us/img504/7...inalql8.th.jpg

RAM mod: 80K or 100K trimmer connected between the points marked in blue. Some cards appear to have slightly higher default voltage. If so, I recommend using the higher value of trimmer (ie...100K).

Thanks to (in no particular order)

Rumon, Miwo, largon, Kyky, pinto, pitya

optional core voltmod points (thanks to Largon)

http://www.xtremesystems.org/forums/...7&d=1196445046

Quote:

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Originally Posted by K404

Post em up here please!

K

---

You all should be able to control your voltage through software. You just need some applications to be able to do it in the near future.

take a look at this
http://www.overclock.net/ati/261940-...-mod-bios.html

I've heard that some versions of ATITool arent holding the settings, plus realtime adjustment mid-bench is always welcome.

:) Software voltage adjustment is good, but I'll always go for a hardmod that I can control.

If I had the cards, id be looking for the mods myself, but cant get a hold of either :( May as well hit the ground running when I invest..

Has the: ATI Radeon 3870 a cold bug ?
I want maybe put a single stage on it. :cord:

So, I removed the stock cooler.

Where I need to look on the PCB ?

Hi. The control ICs are on the back of the card, towards the rear. (opposite end to the monitor plugs)

cant wait for this to be up and running :)

^^ my card comes tomorrow ;) then i try to make some pictures ;)

Ok, sorry I'm bussy with it.

I need more day light. ;)

volt mod bioses do not work.

I will be getting one shortly, if no one has posted by then i will put some pics up.

The core uses the uP6201AQ controller- same as whats used on the 2600

For the RAM: the controller is a uP6101BSA. The voltmod, I suspect will be a variable resistor between pins 3 and 6 of this IC, but i dont know what value yet.

Im hunting for more info at the mo.

I cannot confirm or guarantee that anything i say in these posts will work. I suggest no-one tries what I suggest until someone else can confirm it. If I had a card of my own, id try the mods myself first.

close-up pics (taken by Rumon..thanks!):

http://img161.imageshack.us/img161/4...ntroliczl5.jpg

http://img161.imageshack.us/img161/9...ntrolictk0.jpg

Also posted in VMod section

Carrying this over from the other thread for those who attempt this before more info is acquired, will make it easier ;)

Just for reference, as long as voltage modification points are between ref and ground you can start at a 100k resistor and measure voltage change, then put in a 50k and repeat.. then 25k, 10k, 5k...

When you get one that increases above stock (say from 1.25 to 1.3) then you need to back up one step and thats the best starting point usually.

I use old 3-pin fan connectors to allow fast changing of resistors without having to resolder each one.

LOL I was gonna suggest that, but seems like a cheats way of doing it ;) :D

Hey..whatever works though!

For the core...will need someone with a DMM, and the datasheet to get things moving

I found something. Maybe useful, maybe not. It's a Sapphire HD 2600XT GDDR4. Original here :http://www.topmods.net/articles/?id=104
--- Autotranslation from Russian ---
"For food GPU chip meets the marks - uP6201AQ VLF74P. This 24-hnogy (dvadtsatichetyrehnogy) stabilizer diet, which is very difficult to solder to resist, because the legs are very small. But if those resolved so, it is one leg podstroechnogo resistor at 80 kOm to solder to to the 13rd leg stabilizer, and another to land. If someone is afraid of losing a guarantee, it is possible to use a pencil method to resistor R650 (nominal value of 2.43 Ohms)."
------------------------------------

Quote:

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Originally Posted by K404

The core uses the uP6201AQ controller- same as whats used on the 2600

For the RAM: the controller is a uP6101BSA. The voltmod, I suspect will be a variable resistor between pins 3 and 6 of this IC, but i dont know what value yet.

Im hunting for more info at the mo.

I cannot confirm or guarantee that anything i say in these posts will work. I suggest no-one tries what I suggest until someone else can confirm it. If I had a card of my own, id try the mods myself first.

close-up pics (taken by Rumon..thanks!):

Also posted in VMod section

---

Ok thanks, I can't get sharp foto's. :confused2
http://infomb.googlepages.com/RV670.jpg

if that pencil mod is the same i would definitely not try it as the resistance is way too low for a pencil mod (2.43 ohms)

Scroll up- I think the images in post 12 are fine, "all" we need now is the datasheet for the controller

Quote:

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Originally Posted by K404

Scroll up- I think the images in post 12 are fine, "all" we need now is the datasheet for the controller

---

was about to post the same. The images taken by Rumon look
sufficiently clear I think. :)


EBL

Quote:

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Originally Posted by EvilBellyLint

was about to post the same. The images taken by Rumon look
sufficiently clear I think. :)


EBL

---

If you do not think the images posted by K404 are clear enough you could always grab the actual file itself you can zoom in a fair bit more without losing any image quality

HD3870 PCB 1200DPI (SendSpace)
HD3870 PCB 1200DPI (RapindShare)

been trying to find the data sheet for it but no luck

Hey guys,

I've just obtained the datasheet for the uP6201AQ
http://www.rit.edu/~mkw1084/miwo/387..._03_070829.pdf

:up: :cool:

Quote:

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Originally Posted by Miwo

Hey guys,

I've just obtained the datasheet for the uP6201AQ
http://www.rit.edu/~mkw1084/miwo/387..._03_070829.pdf

:up: :cool:

---

awesome

I don't see why the method for modding a HD2600XT referred in post #15 wouldn't work as we're dealing with the same controller.
Someone with a DMM please measure resistance between the 13th leg and the middle and far-right spot in this pic:

Attachment 68008

I made measurement with a numerical voltmetre (I afflict use a Français/Anglais translator)
Vgdr4
http://img441.imageshack.us/img441/2...vddrby4.th.jpg

Vvpu

http://img529.imageshack.us/img529/3...corewn0.th.jpg

1.89v for the RAM and 1.32 GPU.. both sound right to me :)

god damn id love to get an extra 10% into both of them :D

http://img138.imageshack.us/img138/6...cforresqf8.jpg

Please can someone measure the resistance between the Feedback pin (marked in blue) and GND?

Quote:

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Originally Posted by largon

I don't see why the method for modding a HD2600XT referred in post #15 wouldn't work as we're dealing with the same controller.
Someone with a DMM please measure resistance between the 13th leg and the middle and far-right spot in this pic:

Attachment 68008

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Ok just to say i have not done any measurements for hell of a long time so wait for verification from someone else if the readings sound about right, but if they are way off then well i suck at taking readings :rofl:

DMM setting = 200
For both points measured against pin #13 on the pic i got
0.3
I done it a couple of times at it hovered on 0.7 but it eventually went to 0.3 both points

Quote:

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Originally Posted by K404

Please can someone measure the resistance between the Feedback pin (marked in blue) and GND?

---

DMM setting = 20k
Also K404 i did a measurement on Pin#13 FB and Pin#4 AGND got a reading of

5.12k

I can confirm the same readings as Rumon

#13 + Middle point = .3
#13 + Right point = .3
Resistor that is in-between Middle + Right point = 5.1k ohm

Im guessing the value doesn't change between the middle vs right point is because it only goes through the bottom of that resistor in its path.

And a quick measure of
#13 + #4 = 5.1k

I'm using a cheap Radioshack DMM, but its close enough that we are getting the same readings

vGPU mod (untested):

edited out

Quote:

---

Originally Posted by largon

vGPU mod (untested):

Attachment 68017

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No read from vGPU measuringponits..

Weird. The measuring point should work...
The square pads are on the same plane as vGPU chokes' outputs.

Using a guide on VR-Zone..I was gonna suggest a 100K pot from Pin 13 to ground.

OR a point connected to the FB pin, if it makes soldering easier.

Again....theory, and untested.

INVALID INFO
->

*edited out*

Both Rumon and Miwo got a FB-GND resistance of 5.1K, not 5.1 ohm...or is there a mass mis-communication going on?

Guide on VR-Zone says use a pot of 20x the resistive value of FB pin to GND. Im not pulling numbers out my ass, or making this up as I go along :p:

I admit...taking general 2nd hand info isnt the ideal approach though...

___________________

I agree with the readpoints though

5.1kΩ?
Wowza! You're right!

:O

edit:
Yup.
100kΩ VR would be good.

It's works well! I use a 100K VR between one green point and the ground, actually testing 1.5v vgpu for 975mhz...

Quote:

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Originally Posted by pinto

It's works well! I use a 100K VR between one green point and the ground, actually testing 1.5v vgpu for 975mhz...

---

975mhz core??????

and pics please

Excellent :D seeing as largons green markers include the FB pin, il take that as confirmation it works.

Il update the first post.

Please can you try some resistor values for the RAM mod as well, and we can get that locked down too?

K

Update 995mhz in rivatuner (985 in gpu-z)

http://img98.imageshack.us/img98/8909/3d06152501bc5.jpg

K404 i didn't test the ram now, my goal is to find some log where i can clock both cards i own (stupid limit in overdrive to 885mhz)

Congrats pinto, and thanks for sharing. :toast:

Have you added any relevant info about BIOS flashing to the other thread in the 3D section- it looks like you got past the PLL divider fine!?

excellent :)
hope my soldering skills are up to the job, those points are pretty damn small
What resistance did you set the 100k VR to obtain 1.5vcore? Are you getting any black screens that would be a hint at OVP ?

Next is a vmem mod, hopefully those gddr4 chips scale well

Some optional solder points marked in green:

Attachment 68027

Now it`s time for vmem :D.Is there somebody willing to do that?

It's time for a: 1GHz GPU clock ;)

The RAM mod is provisonally done as well, but we need someone to try: 100K, 50K, 20K etc pots until theres an increase in VGDDR at max resistance.. sorry- I cant be more precise. If you start at 100K though, the card is unlikely to be damaged

well could we get crysis benchmark test @
1280 pixel
4x aa
high details
in win xp

pinto if you could take an actual pic of your mod that would be great, thanks! I just want to double-check before I go about soldering

That what i gve to a french clocker(no pic of the mods, cards are in the case):

http://img46.imageshack.us/img46/6909/10ok5.th.jpg

never volt modded a card before but i'd be willing to do it on these... could do with a simplified guide if at all possible.... ordered duorb coolers ready for the mod...

I as well am willing to do it, I did it back on my 7900GT and didn't have a single problem, card still works today too.

is it possible to get some pics of the final product?

thanks for all the effort you make for this mod. :up:

here is a picture of my 3850 - the
strange: the 2 vgpu measuring points ar missing - so does anybody have a clue how to get the right vcore?
(as i dont have any electrician background i hope its not a silly question :cool: )

http://img502.imageshack.us/img502/2047/dscn2700hp1.jpg

Quote:

---

Originally Posted by pinto

Update 995mhz in rivatuner (985 in gpu-z)

http://img98.imageshack.us/img98/8909/3d06152501bc5.jpg

---

Need more infos:

It's Rock solid at that clocks? Which temperatures did you get? And with which heatsink? They are the max frequencies? Can't bench at 1ghz?

Thank you.

Bye

Quote:

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Originally Posted by oanvoanc

thanks for all the effort you make for this mod. :up:

here is a picture of my 3850 - the
strange: the 2 vgpu measuring points ar missing - so does anybody have a clue how to get the right vcore?
(as i dont have any electrician background i hope its not a silly question :cool: )

http://img502.imageshack.us/img502/2047/dscn2700hp1.jpg

---

The voltmod will be the same.

The Choke layout looks to be different to the 3870. Please can you get a picture of the whole of the back of the card?

Worst case scenario will be- take VCore reading from the FETs under the separate heatsink- this reading will be the average voltage so to speak. It will be ballpark right, but wont take into account any droop.

:) K

Quote:

---

Originally Posted by K404

The RAM mod is provisonally done as well, but we need someone to try: 100K, 50K, 20K etc pots until theres an increase in VGDDR at max resistance.. sorry- I cant be more precise. If you start at 100K though, the card is unlikely to be damaged

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Where?:confused:

pinto whats ur idle and load temps(celsius) @ 1,5v/985mhz?
and water temps if u pleas(before the mod was done if possible)

just wanna know if my water loop can handle it before i start modding

thanks for a grait work done guy's been waiting for this

Quote:

---

Originally Posted by oanvoanc

here is a picture of my 3850 - the
strange: the 2 vgpu measuring points ar missing - so does anybody have a clue how to get the right vcore?

---

See those two ceramic caps connecting the copper planes (= lighter areas on the PCB) where the vGPU measuring points should be?
Try poking the pole that is farther from the GPU with a DMM probe... ;)

Quote:

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Originally Posted by quake6

Where?:confused:

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1st post dude! :)

Quote:

---

Originally Posted by Amrita

pinto whats ur idle and load temps(celsius) @ 1,5v/985mhz?
and water temps if u pleas(before the mod was done if possible)

just wanna know if my water loop can handle it before i start modding

thanks for a grait work done guy's been waiting for this

---

Now i can bench at 1ghz for 1.52v, with simple waterblock in my cpu loop i have 36°c idle and 40°c full

I took the advice of Pinto for the vmod.thus I am in watercooling under 1.52V, my frequency is 1012/1323. The temperature of the core is of 44° in full and 41 in idle.

http://img132.imageshack.us/img132/7...9991368sf7.jpg

wow great stuff guys :)

i have high hopes for the RAM too :)

think i will be fine, i will run way hotter then u but i should still be within good temps
if not i will try reseat my waterblock and maby doo some mod's to the loop
ither way i'm doing this
just need to go get me a new pensil and find me a 100k resistor on monday
again thanks for being guinnie pig's
made my day ^^

can anyone please take a pic of what the mod looks like? I want to mod mine, but I have no idea what to get, or what it should look like.

hit 1GHz on air :) . A big thanks to K404, Largon, and everyone else who contributed! 1.53v measured

http://www.rit.edu/~mkw1084/miwo/3870/3dmark1GHz.jpg

hi k404

here the picture of the whole card.

http://img101.imageshack.us/img101/7069/img0283af0.jpg

Hey Oanvoanc :D From the looks of things the mod will be the same. The control ICs and the surrounding SMC layout look the same.
A bit of an assumption, I know, but realistically ATI wont redesign the PWM gear between 2 cards that are so similar.

The VCore readpoint will be different though :)

K

If both cores are practically the same, and only the clock speed is different, shouldn't the 3850 be able to reach 1GHz too? or is it a matter of ... quality of chip?

The 3850 has some components of lower quality, the vregs...wich I think will not allow it to reach same clocks as the 3870.

If I were you i'd try to shade this resistor, and see what happens
I want to buy this card, just let me know if it works

http://img155.imageshack.us/img155/3...3850rx9.th.jpg

I have my 3850 stable @ 776/1125, when I hit 800 theres not enough voltage, the temps I get are 65C full load and 31C idle with the fan @ 70%

http://img221.imageshack.us/img221/7940/3850eq3.jpg

it seems like the 3850 has a lower GPU clock and mem voltage than the 3870.

Kain, i think you should test a game like Crysis while keeping the RivaTuner monitoring up in the background, just to test out the VRAM filled out and working like crazy, cause i think the max stable, unmodded, RAM speed i saw on the internet was 1050MHz, and 776 for the core.

Hope someone tests a V-Mod for the 3850 before i get it next week.

I have only tested on battlefield 2 and need for speed pro street so far but if i up the Vcore to 784 card goes bonkers, it needs more voltage.

Can someone pretty please explain what I need to do to vmod my 3870? I see the pretty 3DMarks, but I dont see what exactly I need to solder on to get the mod up.

Thanks,

Ryan

You need a variable resistance that has 100k and lower, and then solder it onto the 2 points specified in the first post.

Maybe someone can explain better!

Quote:

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Originally Posted by os008

You need a variable resistance that has 100k and lower, and then solder it onto the 2 points specified in the first post.

Maybe someone can explain better!

---

thanks. where can I find the variable resistor? Would radioshack have it?

Thanks!

Ryan

Ryan- supposedly they do.
There was talk in the 8800GT thread about it.

As for pics as to what it should look like, something like this but on a red PCB with a 100k pot and to the points marked in the first post of THIS thread. That picture is of a 8800GT Vmod.

Quote:

---

Originally Posted by KainXS

I have my 3850 stable @ 776/1125, when I hit 800 theres not enough voltage, the temps I get are 65C full load and 31C idle with the fan @ 70%

[IMG]ss[/IMG]

it seems like the 3850 has a lower GPU clock and mem voltage than the 3870.

---

Hi, which 3850 have you got? Also, does rivatuner overclocking work with CCC installed?

bring on the DDR3 volts! :)

Quote:

---

Originally Posted by ghost101

Hi, which 3850 have you got? Also, does rivatuner overclocking work with CCC installed?

---

I have the powercolor version

Im going to post some pictures of the back of the pcb to help you guys with vmods later

edit

3850

http://www.i-imagehost.com/uploads/e7ad70078b.jpg

yes I know its huge

So I see the pic with the green and purple dots what are you soldering to do this exactly? I'm confused

Green = soldering point for outer leg of a VR
Blue = ground = solder middle leg of a VR
Purple = vGPU measuring point (red probe of a DMM to purple, black probe to ground)

Christmas Project: Vmod 3870 with the DuOrb :D

heres the 3850, imagehost keeps deleting it

http://www.yourfilehost.com/media.ph...27P1010374.JPG

Quote:

---

Originally Posted by K404

Updated:

These mods need more testing, but initial results suggest they work fine.

Mods are carried out at your own risk. I will not take responsibility for any voltmods gone wrong. No-ones forcing you to mod your cards and invalidate your warranties.

http://img119.imageshack.us/img119/8...inalic3.th.jpg

http://img504.imageshack.us/img504/7...inalql8.th.jpg


Thanks to (in no particular order)

Rumon, Miwo, largon, Kyky, pinto, pitya

optional core voltmod points (thanks to Largon)

http://www.xtremesystems.org/forums/...7&d=1196445046

---

Okay so just simplifying here, All you need to do is solder a 500k ohm resistor inbetween those two points?

Quote:

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Originally Posted by slugzkea

Okay so just simplifying here, All you need to do is solder a 500k ohm resistor inbetween those two points?

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!bump

Electronics store closes in 2 hrs...

Quote:

---

Originally Posted by slugzkea

Okay so just simplifying here, All you need to do is solder a 500k ohm resistor inbetween those two points?

---

Hmmm... I think you should do some more reading before going for the mod but here you go, VR from one of the green points to the blue point (which is ground), the two violet points are reading points as it says.

How about a pic of the completed mod? The diagram says one 500 k ohm resistor and indicates where to solder the ends (one is ground).

all i want to do is confirm that all you are soldering is one resistor?

Quote:

---

Originally Posted by slugzkea

How about a pic of the completed mod? The diagram says one 500 k ohm resistor and indicates where to solder the ends (one is ground).

all i want to do is confirm that all you are soldering is one resistor?

---

If you read the thread, it is suppose to be a 100k VR.
All you need is the card, soldering iron, solder, 100k VR, some wire, preferably double sided adhesive and a DMM.

Pinto show us a pic of your mod, We want to see what points u used. What was your finally resistance value to achieve which vcore?

didnt do a volt mod but i used a modded bios and i got 815/2000 out of my 3850..

http://service.futuremark.com/compare?3dm06=4019858

used this bios: http://xxx.iax-tech.com/video/3800biosmod/01.htm

its screaming for more volts i reckon....

so who is going to fallow through with pics of the vgpu mod?

and why are u guys ordering duo orbs? the zalman vf900 iis better IMO and u can control the fan speed.

just a suggestion.

vf900 isnt better than duo orbs...

i ordered a S1 Accelero and a 120mm cooler...für my 3850..and this is realy "cool" ^^ its better than the Zalman VF900

Just a quick update:
Seems temps are holding me back from reaching full 1GHz stability atm. For instance, at 1.53v 1GHz core, I do not artifact in ATITool until I cross 50C. After a run of 06' my load temps are 55C. I've dropped the vcore down to 1.46v for 24/7 use at 945MHz Core. My load temps after 16hours is 48C, and at this setting it wont start artifacting until I hit above 60C.

My current cooling setup is an Accelero S1 w/ low speed 140mm Yate Loon. Sometime this week, I plan on replacing the Ceramique I used with Coollaboratory Liquid Pro and getting some more airflow across the fins by removing the black plastic caps on the S1. Hopefully that will let me do 1GHz for 24/7 usage on quiet Air :)

A pic (using my uber1337 paint skills)

Please ask yourself...if you are unsure how voltmods work or how they should be attached....should you be trying the work? Remember- the responsibility for the mod lies with yourselves. If you kill your card, its YOUR fault, because the mods have been proven to work.

http://img233.imageshack.us/img233/8...iousoj9.th.jpg

Quote:

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Originally Posted by LordEC911

If you read the thread, it is suppose to be a 100k VR.
(...)

---

100kΩ is about the minimum, higher valued VR allows minimum voltage as close as possible to stock but they also cause inaccuracy while tuning (larger granularity).

But yeah, 500kΩ might be a bit inconvenient.

Quote:

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Originally Posted by ryanmartini

thanks. where can I find the variable resistor? Would radioshack have it?

Thanks!

Ryan

---

I don't know as i'm from Egypt, you have to ask someone who's from your country :).

how successful is the vmem for ocing?

To keep from shorting the GPU voltmod you guys might also want to look at putting a fixed resistor in series with the VR... I would say a 10K fixed should do for most but it might be a bit high for getting 1.6v+...