ATI 3850/3870 Voltmod thread

[patrickadizzle]

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.

[ryanmartini]

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

[oanvoanc]

thanks for all the effort you make for this mod.

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 )

[MonsterMash]

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

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

[K404]

thanks for all the effort you make for this mod.

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 )

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

[quake6]

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

Where?

[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

[largon]

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...

[K404]

Where?

1st post dude!

[pinto]

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

[kyky]

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.

[Sage]

wow great stuff guys

i have high hopes for the RAM too

[Amrita]

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 ^^

[ryanmartini]

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.

[Miwo]

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

[oanvoanc]

hi k404

here the picture of the whole card.

[K404]

Hey Oanvoanc 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

[os008]

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?

[Clint]

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

[Niccolò]

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

[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%



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

[os008]

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.

[KainXS]

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.

[ryanmartini]

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

[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!