ATI 3850/3870 Voltmod thread

[K404]

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.





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)

[96redformula]

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.

[hstuehmeyer2000]

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

[K404]

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..

[nFo]

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

So, I removed the stock cooler.

Where I need to look on the PCB ?

[K404]

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

[Sage]

cant wait for this to be up and running

[Cha0s]

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

[nFo]

Ok, sorry I'm bussy with it.

I need more day light.

[STEvil]

volt mod bioses do not work.

[kemist]

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

[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

[STEvil]

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.

[K404]

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

Hey..whatever works though!

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

[pitya]

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)."
------------------------------------

[nFo]

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.

[Timbosan]

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)

[K404]

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

[EvilBellyLint]

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

[Rumon]

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

[Miwo]

Hey guys,

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

[EvilBellyLint]

Hey guys,

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

awesome

[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:

[kyky]

I made measurement with a numerical voltmetre (I afflict use a Français/Anglais translator)
Vgdr4


Vvpu

[Sage]

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