ATI 3850/3870 Voltmod thread

[chp]

Voltage at boot is different than when running 3D app; run 3DMark or ATI Tool artifact tester then measure.

Thanks.

[gurusan]

Hi gurusan,

I think have the same Powercolor as you (I think it's the HD3850 PCS-512) and I've done the VMOD but I can't pass the 823MHz stable @ 1,47V without black sceens durring 3D tests after 1 to 5 mn (sometimes immediately)

I tried also 864MHz @ 1,52 with no luck

So, I have some noob questions (hope you'll help me):

1) where, when and how do you test your volts. I mean I use a MM to test between the points shown in the pictures but I don't know if I need to be running a 3D app to test or not.

2) What bios do you use? For my part, I tried many and the one wich shows the best performance in 3DM06 is the HIS HD3850 IceCube one (xxx.O77.xxx).

I removed the original Powercolor cripled cooler and put an original ZeroTherm 810 wich allows the fan to rise the rpm depending of the heat.Now, my temps aree fine in load (atitool's artefact scan) with max 65 - 67 degres @ 1,47V for 823MHz.

1) I use the point marked in green to measure vGPU

2) I use the version 71 HIS IceQ3, I've had the best results with this
http://rapidshare.com/files/94631983/ati.rar.html

[chp]

1) I use the point marked in green to measure vGPU

2) I use the version 71 HIS IceQ3, I've had the best results with this
http://rapidshare.com/files/94631983/ati.rar.html

Thanks gurusan, I'll try it asap.

[gurusan]

Thanks for the help clocking my 3870 guys...added it to my 3850 and got a pretty respectable score for a dual core:

[Eldonko]

Not bad at all.

[bl1zZ]

Any working vMem mod for hd3870?
Didnt find anything...
Pencil would be the best for trying if it worths soldering it.

[G.Foyle]

I have one Saphire card and one ASUS; on Sapphire, I can go to 1.4V without a problem. On ASUS, card shuts down as soon as I hit 1.295V - it seems like OVP is kicking in already. Can anyone with ASUS card confirm that?

I also thought of making OVP mod; according to this image:

it seems that pin 16 of uP6201 is Power Good sensing, which from my experience should also control the OVP. Anyone got any ideas? I'll take measurements when I get back home.

P.S. It would help me if someone still had the datasheet Miwo posted on 1st page.

[Eldonko]

I thought it was a few resistors that controlled OCP. That is what Sham modded anyway. I suppose it could be different for each card tho.

[G.Foyle]

I don't think it's OCP, it happens even in BIOS, with GPU cold and idle, and always at the same voltage.
I really need more volts, I'm 500pts away in 3dm01 from next place on HWBot

[bl1zZ]

@ Which rank are you?
Hd3850 or 3870?

[G.Foyle]

14th in 2x Radeon 3850 (hardware rank), 2nd in Poland
http://www.hwbot.org/result.do?resultId=719830

[bl1zZ]

Ah ok
I go for single HD3850
Atm 8th @ 06 I think
Got 65k @ 01 Single Card

[xixou]

Power OK Indication. POK is an open drain output used to indicate the status of the voltages
on SS pin and FB pin. POK will go high impedance if V FB > 075% of reference voltage after soft
start ends.

[MikalCarbine]

Is the vGPU mod possible with a 50k ohm potentiometer? My card is under water and I plan on running ~1.5v

[ceemic]

MikalCarbine, which card?
My Giga 3870 has 100k pot (96,7k actual) and I get now 1,477V 2D and 1,519V 3D. I think 50k is a little bit too dangerous (over 1,55V 2D probably).
http://ceemic.pri.ee/hardware/hd3870/hd3870mod1.jpg

BTW other guys too: my WR card is dead

[MikalCarbine]

Sorry for not elaborating, it is on a Sapphire 3870, I've gone to several radioshacks and for some reason they no longer carry potentiometers over 10k I have two 50k lying around but would rather not tie them in series because I'd like to do both vmem and vgpu.

I do have a pack of resistors lying around that I could tie in series but if I choose too high of a resistor I would have to physically replace it later

Does anyone know how Jaan mounted his secondary PCB for his volt mod?

[ceemic]

MikalCarbine, PCB has several holes in it. Jaan used one of it: http://img234.imagevenue.com/img.php..._122_358lo.jpg

I can ask him, but probably there are few paper washers...

[Barr3l Rid3r]

MikalCarbine, which card?
My Giga 3870 has 100k pot (96,7k actual) and I get now 1,477V 2D and 1,519V 3D. I think 50k is a little bit too dangerous (over 1,55V 2D probably).
http://ceemic.pri.ee/hardware/hd3870/hd3870mod1.jpg

BTW other guys too: my WR card is dead

how did you kill it? have u used sapphire 3850 bios for benching or other one?

[ceemic]

Barr3l Rid3r, actually, its not completely dead. Something is wrong with thermal sensor, 'cos it shows picture only when booted "cold". After restart, PC boots up, but no picture. When I close PC for atleast 5min for cooldown, it works again. 3D is OK also (some misterious crashes tho...). I removed Vmod and flashed back original BIOS also. I used the Shappire 3850 one yes...

[kup]

Hey guys, I've got a GeCube 3870 X-Turbo Edition here and it only has the 3D circuits, not 2D.

Will the vGPU mod still be the same as in the first post? I've read through the thread from start to finish and I can't seem to spot any reference to my card?

[kup]

No worries guys, I worked it out myself. It was the same as the pencil mod for the best Solder point. And DAMN those points are tiny on this card...

[kup]

1) I use the point marked in green to measure vGPU

2) I use the version 71 HIS IceQ3, I've had the best results with this
http://rapidshare.com/files/94631983/ati.rar.html

Thanks gurusan, I'll try it asap.

Gurusan, how did you find this bios? Did it improve your clocks at all? Or performance per clock?

[TheMan89]

Hello guy´s

I have made the vgpu mod on both mine HD3870 one Club3d and one Asus and i have flashed in a better bios thats unlocked from the 862mhz lock.

But now i have a new problem. The cards are running with WC and i have 1,4v in 3d mode so they make easy 950mhz on that voltage. But i cant overclock card number 2 only number one in rivatuner and other programs. And if i use CCC i only get to 885mhz on the core and thats even not near what i want. I have pushed made a 3d06 round in 1077mhz on the core at eatch card i singel so i need some kind of mod to any program so i can overclock them in win to 1077mhz.

Any suggestions?

[ceemic]

TheMan89, sadly only CCC allows to overclock crossfire

[TheMan89]

It´s Really bad i think... I hope someone make a fix for rivatuner or something so i can overclock them without flashing the bios.