ATI 3850/3870 Voltmod thread

[afireinside]

100k... All I have right now are 50k Anyone know how many ohms are needed for ~1.5vgpu?

Any vmem mod found yet?

[K404]

dude...VMem mod is DONE the only thing missing is the ideal pot value.

Someone should take the initiative and friggin TRY it.

Start with 100K....tune down until it bites then measure the resistance.

Jeeezzzzzz

AFI...I know you KNOW this!

[/exasperation]

[afireinside]

Ah sorry didn't check the thread. Just got my cards and I've been busy trying to get them to work in games. I'd try if I had 100k VRs but I don't.

And no, I don't know anything about volt mods.

[purecain]

send your cards back if they dont work in any games, or elaborate...

[afireinside]

send your cards back if they dont work in any games, or elaborate...

They work... Just not well. Ut3 drops to 30s a lot and CF won't work in hellgate london or crysis.

[largon]

What is the resistance between vMEM solder points?
Around 4kΩ?

[purecain]

crossfire does work in crysis on mine, must be a driver issue with your rez and hellgate london works fine for me aswell in crossfire... looks like your having some bad look.
try returning your cards as something is wrong at your end...
are you on vista and have you installed the multigpu hotfix????

[afireinside]

crossfire does work in crysis on mine, must be a driver issue with your rez and hellgate london works fine for me aswell in crossfire... looks like your having some bad look.
try returning your cards as something is wrong at your end...
are you on vista and have you installed the multigpu hotfix????

MultiGPU hotfix... That might be a good idea

[JamesBong420]

hi k404

here the picture of the whole card.

here you go at least for the vcore.

[Klimpen]

Hi all, I see a few that want a picture taken AFTER the vGPU mod has been done.
I can provide that because I understand what to do, I have a 3870, I have very good experience with soldering small
components (even SM-components) and of course I have a camera and a webhost..
The only thing I'm missing is a VR of 100kOhm. It's sunday here and EVERY store is closed.
I will ask my friend at work tomorrow for a 100kOhm VR.

Even though I have stock cooling on right now I have a EK waterblock on order so that should be settled in a couple of days.

When I'm done with the mod I will try to take several pictures and help out as much as possible.
Ohh, I have one question though, when I'm done with the mod and everything is ready to go!
How do I know where to start with the VR.
Is it just a matter of trial and error? To start with it set to max resistance (100kOhm) and then
slowly turn it "down" and measure the vGPU readout until I get what I want (about 1.5v)?
I have actually pretty good knowledge in soldering and electronics but have never done a vMOD of this kind before


##EDIT##
I have to chose from one of the following ones, any opinions?


type 44 Y for SM with only 10 turns



type 64 with 15 turns



Type 67W with 20 turns



Type 89P with 20 turns

[Amrita]

i went with the 15 turn's one was acurate enough actualy perfect
a 20 i think u will hate, to mouch hassle turning hehe

as for finding the right resistance u got it right set it too max resistance then solder it on and boot up
messure the volt and start turning a round at a time and messure untill u get a new readout then turn with care untill u hit the sweet spot^^

[Mayk-Freak]

2 x 3870 Volt-Mod

[JamesBong420]

now thats what i call CLEAN!!!!

[jimmyz]

somebody beat me I see lol. I am still limited to 864 by bios but stilt said soon the 3850 bios will be out. what's worse is i can't get any utility to clock the second card past 770 core.
[IMG][/IMG]

[Mayk-Freak]

C2D@4180MHz -4GB Crucial- 2xHIS HD3870@1012/1341MHz

Vista 64Bit

[Unoid]

Nice clocks with dual voltmodded 70's.

[pepinorang]

dude...VMem mod is DONE the only thing missing is the ideal pot value.

Someone should take the initiative and friggin TRY it.

Start with 100K....tune down until it bites then measure the resistance.

Jeeezzzzzz

AFI...I know you KNOW this!

[/exasperation]

I'm on HD3870 (one card 930/1340 and the other 902/1340 ALL stock) I'm just awaiting EK waterblocks and trimmers to do both mods don't worry about it I'm adventurous so I take the initiative will give my feedback here next week I think

Bye
p€p|n0r@ng

[kemist]

I'm on HD3870 (one card 930/1340 and the other 902/1340 ALL stock) I'm just awaiting EK waterblocks and trimmers to do both mods don't worry about it I'm adventurous so I take the initiative will give my feedback here next week I think

Bye
p€p|n0r@ng

What are you using to clock the cores? Atitool doesnt work, rivatuner works, but only for one core (for me at least), and ati tray tools didnt appear to work.

Ahh ok, was using ati tool .27 B3, will give it a try when i get home, thanks.

[JamesBong420]

atitool .27 b4 works for me. 3850

http://www.techpowerup.com/wizzard/ATITool_0.27b4.exe

[pepinorang]

What are you using to clock the cores? Atitool doesnt work, rivatuner works, but only for one core (for me at least), and ati tray tools didnt appear to work.

Ahh ok, was using ati tool .27 B3, will give it a try when i get home, thanks.

Rivatuner works properly for me but there is a "procedure" to follow if you want to clock CF but for me now it's bios-modded

[kemist]

Quick question.

Would it be bad if i were to bridge these two points with solder? It looks like the are connected by the pcb and so it wouldnt matter if the were bridged?

[oanvoanc]

thanks for your help k404.

here my mod (i didnt use it yet because i already maxed the card out under ln2 without "activating" the mod -> 857mhz)




this is a result under liquid nitrogen - without any voltmod.
so you dont need this mod under cold unless the vco clock divider problem has been solved:





okok - big surprise - big surprise!

today i tested the card just with watercooling - still without activated voltmod.
i kept the temperature below 21 degree celsius (load) and had a stable 857mhz core frequency..... very interesting

[Unoid]

why interesting? use the bios that fixes the probelm and 1ghz should be your goal!

[oanvoanc]

i dont think this would work.
i heard that this bios would just work for the hd 3870.

[largon]

Quick question.

Would it be bad if i were to bridge these two points with solder? It looks like the are connected by the pcb and so it wouldnt matter if the were bridged?

You can do that.
These points are connected via PCB trace already.