ATI 3850/3870 Voltmod thread

[Clint]

Those ultra durable gigabyte 3850 and 3870 have the same layout, right?
Difference comes in with caps and memory, anything else?
Id like to try vgpu on my 3850, but since its my first vgpu id like to be extra sure.

Yes, they have the same layout!

I suspect they will perform pretty much the same once the caps are changed, the mems on the 3870 will do 1000MHz and the mems on the 3850 will land on 850MHz. Memoryoverclock doesn't affect performance that much on these cards .
.

[ceemic]

http://ceemic.pri.ee/hardware/hd3870/

[Clint]

http://ceemic.pri.ee/hardware/hd3870/

Very very nice, thanks!

[ceemic]

Mine Gigabyte has slightly different layout:
http://ceemic.pri.ee/hardware/hd3870/hd3870_13.jpg
http://ceemic.pri.ee/hardware/hd3870/hd3870_14.jpg

Where are the exact vmod points?

[Barr3l Rid3r]

Mine Gigabyte has slightly different layout:
http://ceemic.pri.ee/hardware/hd3870/hd3870_13.jpg
http://ceemic.pri.ee/hardware/hd3870/hd3870_14.jpg

Where are the exact vmod points?

vgpu - Yes

Clint, sorry about the delay, I was traveling...

Hey guys now we need a 3870 DDR3 unlocked bios for that card, I want to use CCC cause NVtuner use 3D voltage (1.34V) when on, all the time even at 2D. 3850 is limited at 720MHz in CCC any possible fix?

[ceemic]

Ok, a little specific questions:

Is the Vgpu mod point correct?
http://ceemic.pri.ee/hardware/hd3870/hd3870_13_1.jpg
Vcore values seems OK...

2,13V mem is correct?
http://ceemic.pri.ee/hardware/hd3870/hd3870_14_1.jpg


I'll try the 3850 BIOS asap and let You know, if I find something interesting

[ceemic]

I flashed my 3870 w/ 3850 BIOS, edited clock to 780/950 and I got now 1,339V in 2D and 1,381V in 3D

[RealyPssd]

Cool, glad to see it worked.

If only I had a 1.381v BIOS for my HIS 3870

[Barr3l Rid3r]

Ok I've found a solution for Gigabyte HD3870 512MB DDR3 Qimonda.... System setup

VGA Gigabyte HD3870 512MB DDR3 Ultra-Durable vGPU + CoolerMod AiR
Default 780/1900Mhz @ 1000/2150Mhz
Intel 975xbx BadAxe 417Mhz fsb
Core2 Duo 6600 @ 3.8GHz Single
2x 2GB (4GB) Corsair 667Mhz @ 700Mhz

1 - Original Ver 70 locked bios 1.22V @ 1.34v 3D

maxed out at @859/2100Mhz (11800 Marks 3D06)

2 - Used a Sapphire 3850 512MB DDR3 Qimonda Bios
Ver 71 Unlocked Bios 1.22V ( http://www.techpowerup.com/vgabios/2...12.071108.html )

+ Editor to set 1.32V 3D And now I got 1.38V in Multimeter
@895/2100Mhz (12200 Marks 3D06)
( http://www.computerbase.de/downloads...tor/?url=17592 )

Original





Moded









3 - @ 1000Mhz/2150Mhz - 1.66v Unlocked Sapphire Bios - (13261 Marks 3D06)
http://service.futuremark.com/compare?3dm06=5333029

[lowtcell]

Did the pencil mod an my Sapphire 3850. Resistor down to 1038ohms gives me 1.376v. This gave me stable 860 gpu 1020 mem. With 860 gpu and 1050 mem, 3dmark06 crashed half way through. I have not messed with the mem voltage yet, my stock voltage is at 2.02v.

[pablo NZ]

My Gecube PCB is slightly different to most others. It does not have the resistors that are used for most other pencil mods. As well as that, bios voltage mods do not work for this board (deafult always stays 1.25v in both 2d/3d).

Anyhow here is the pencil mod that works for me. BE WARNED - do not reduce the resistance too much - one or two strokes of a 2B pencil is enough and always use a volt meter. My first attempt ended in 1.76v being fed to the GPU.

Default Resitance OF 2.44K gave me 1.25v and 770Mhz limit
Modded Resitance at 2.2K gives 1.42v and 877Mhz Crysis stable

Hey man, I think I have the same card (gecube 512mb 3850 x-turbo III). Do you happen to know why you can't change voltage through bios? Do you know if a different brand bios will work to change voltage? I just hesitant to try pencil mods, but might give it a shot if all else fails...

[nikk]

vgpu mod on hd3850:



up to 1ghz, only for short rthdribl run 1.58v



06 @ 945mhz 1.53v http://service.futuremark.com/compare?3dm06=5299670
05 @ 958mhz 1.54v http://service.futuremark.com/compare?3dm05=4018807

with accelero s1 + delta 120mm

[Random Murderer]

vgpu mod on hd3850:



up to 1ghz, only for short rthdribl run 1.58v



06 @ 945mhz 1.53v http://service.futuremark.com/compare?3dm06=5299670
05 @ 958mhz 1.54v http://service.futuremark.com/compare?3dm05=4018807

with accelero s1 + delta 120mm

it looks like you connected the vgpu measure point to one of the fins on the accelero. is this true?

[nikk]

it looks like you connected the vgpu measure point to one of the fins on the accelero. is this true?

of course not, why would i do that

the measure point end up in a cut molex

[Barr3l Rid3r]

of course not, why would i do that

the measure point end up in a cut molex

Because u coul measure the vgpu on any fin then...

[raibemunn]

Barr3l Rid3r, is your vgpu spot same as in the ceemic's pic?

/edit. oh damn he updated the pic, pressed F5 accidentally :p
anyway, you used the same spot?

[ceemic]

raibemunn, yes, same spot: http://www.xtremesystems.org/forums/...=176689&page=2

Ega sa eestlane ei ole? "Kahtlane" kasutajanimi

[lowtcell]

Finally achieved my goal of 12K 3DMark06. Smoked my previous best of 11,919 with 12,394 only 1.376 volts and 850 mhz clock. Now to go for 13K because my OCD will never let me stop

http://service.futuremark.com/compare?3dm06=5334775

[pablo NZ]

Ok so i did the same mod as ORVILLE on my gecube card, and now crysis stable at 810mhz with 1.38v (2.25k shading)

Very happy

[ORVILLE]

Hey man, I think I have the same card (gecube 512mb 3850 x-turbo III). Do you happen to know why you can't change voltage through bios? Do you know if a different brand bios will work to change voltage? I just hesitant to try pencil mods, but might give it a shot if all else fails...

Bios voltage change just doesn't work on my board. I tried many other bios' and just wasted my time.

[pablo NZ]

Do I need to do anything to protect this pencil-shaded resistor? I'm worried that if I rub something against it whilst moving stuff around my case it might alter the resistance.

And should I be putting a little heatsink on the voltage regulator or anything?

[jimmyz]

Do I need to do anything to protect this pencil-shaded resistor? I'm worried that if I rub something against it whilst moving stuff around my case it might alter the resistance.

And should I be putting a little heatsink on the voltage regulator or anything?

A little clear fingernail polish will seal and protect the pencil mod, and on a side note an egg will remove the blood stain from the beating you will no doubt get buying nail polish.. best part of it is it can be removed later when you sell it.

[PanMaster]

I've read all 20 pages and there is not a single mention of Triplex 3850s. So here it is:

I have not the foggiest clue which resistor would alter the GPUvcore.

[jimmyz]

PanMaster, go to the other end of the card. the power plug end and take a pic from above and as close up as possible. the power circuits are the money shot. look for a similar shaped chip to the one you have pictured.


edit: Sorry I just noticed the crd isn't a ref. design , lol the pic you posted is the proper area.

[PanMaster]

Theres nothing on the other end jimmyz. Its a really strange PCB.
See