HD3870 Bios Modding (Hex Editor - Clocks - Voltages)

[Janchu88]

Hi,

after someone wrote to me who sold his 2900Pro and bought a HD3870 he asked me if i could mod his bios... so i took a closer look and with the knowledge from the 2900 modding the relevant offsets were found after a few minutes...

To understand the Basics of this modding please refer to the 2900 1st Post please... after you understood there how to proceed this should help ypu edit your own Bios...

Open your Bios in a Hex-Editor und search for the memory clock because its the same in all Power States (Mem clock as hex value is d8 b7 01)

after some searching i found this block:



and after some conversions i finally could figured this out



On one 3870 we could confirm that it worked, Here is the Bios File:

2D: 250/1126 with 1,0v (1,241v is default)
3D: 850/1250 with 1,327v (1,327 is the default voltage)

http://rapidshare.com/files/73980710/test.rom.html

What we could see, that his Overdrive didnt work afterwards, dunno why...

In this Bios i did not correct the checksum - it worked though... but perhaps it is like with the HD2900 cards, that some need a corrected checksum. We will see.

[super dank]

I had a feeling they would use a similar format

I hope people that actually have the cards will help refine this.

I'm not sure you have it labeled exactly right, the 3870 uses 3dmode in windowed apps (unlike 2900) and may have a designated setting. It may be the third set of 3dclocks at the top of what you have labeled for thermals.

I really have no idea since I'm not playing with one, but that is my suggestion.

[Janchu88]

I had a feeling they would use a similar format

These were my first thoughts, when i saw the values... I do not have a 3870 and I can´t play around with the values. It is just as you said

I hope people that actually have the cards will help refine this.

[KainXS]

If you can modify this 3850 bios with higher volts from IAX Tech then I can try it. I checked a hex editor on it and its the same concept

http://www.iax-tech.com/video/3800biosmod/03.htm

[HousERaT]

If someone can get a working 3870 bios with 1.4v and 1.5v in 3D mode I'll be willing to try them out.

[pepinorang]

I have tried this mod today and 900/1340 work ok for me (even 930/1340 but I go for CF and only one of my cards can do this stock) but seems you cannot raise voltage with any values of the screen only decrease

EDIT: I can raise the 2d state voltage but 1,4v/1,45v = 1,33v multimeter (seems it's the limit)

Bye
p€p|n0r@ng

[MorGo7h]

Bios Vmodding doesnt work on these cards Only hardmods.
Does 900/1340 work on both cards?

[pepinorang]

Bios Vmodding doesnt work on these cards Only hardmods.
Does 900/1340 work on both cards?

Yeah 900/1340 work 100% stable on both cards with stock cooler, I even tested 930/1340 on one card with success but the other card can't do this with stock vgpu...

Bye
p€p|n0r@ng

[alexio]

*HD3850 256mb all voltages to 1.327V (HD3870 3D level)
*Extremely experimental (need PCI card or blind flash if something goes wrong)
*checksum not fixed (most certainly not a problem)

Test at your own risk:
http://rapidshare.de/files/38011915/..._vmod.bin.html

EDIT: Clock lock at 862mhz core

[~Woomack~]

*HD3850 256mb all voltages to 1.327V (HD3870 3D level)
*Extremely experimental (need PCI card or blind flash if something goes wrong)
*checksum not fixed (most certainly not a problem)

Test at your own risk:
http://rapidshare.de/files/38011915/..._vmod.bin.html

EDIT: Clock lock at 862mhz core

I checked this bios on Sapphire 3850 256MB and I have 1,24V in 2D and 1,28V in 3D

[os008]

I think i read somewhere that BIOS V-Mods don't work, did you test that BIOS?

[alexio]

Maybe the bios vmod will work if you change the device id to "HD3870" from "HD3850". I will update shortly after I have made this mod. After all the driver is responsable for assigning the vcore so it's worth a try atleast

It's just weird that the driver doesn't read the correct values from the bios.

[Miwo]

BIOS vmodding didn't work on the 3870. It was one of the first things we tried in the unleashed thread about 3 weeks ago. I've tried modifying the voltage tables up to 1.5v, and it does not budge. The checksum changes as soon as you modify anything on the original bios, and an incorrect checksum will give you a blank device ID / info when you try flash. The -f flag forces it, but you still dont get any change in voltage. guess has a tool to modify powerplay tables / clockspeeds, but he is under NDA and that tool is likely not going to be public.

So, pretty much if you want working vmods you either do hardware mod, or wait for w1z to get working software control in the next version of ATITool. You could probably try figuring out how to get a matching checksum and see if that makes bios modding work. But rather that wasting so much time to do that, imo you could just hardmod it and be done with it...

[alexio]

*edit*

[os008]

Here's a thread talking about BIOS Checksums, in German though, the English translation below is very bad, didn't understand it well, so if anyone can take a look and tell us what he concludes?

http://www.area3d.de/forum/showthread.php?t=2545

http://translate.google.com/translat...hl=en&ie=UTF-8

Thanks.

[2DIFF]

Well it says that testing for the HD 3870 Bios can't be done because they don't have a card, they're looking for testers.
I have two 3870's, one form Gigabyte & one from HIS running CF. I just think it's worth to wait a little until threre's a new driver version, 'cuase the latest one is as young as the card itself. Greetings from Switzerland

[ChromeGunner]

anyone tested this bios yet???

[KWSW]

anyone tested this bios yet???

yup interested to know that as well

[MonsterMash]

http://rapidshare.de/files/38027384/test2.rom.html

Checksum corrected, think it's ok now. Device id = HD3870 NEED TESTERS

How did you take the correct checksum?

[fhpchris]

http://rapidshare.de/files/38027384/test2.rom.html

Checksum corrected, think it's ok now. Device id = HD3870 NEED TESTERS

Ill test it this weekend

[os008]

*HD3850 256mb all voltages to 1.327V (HD3870 3D level)
*Extremely experimental (need PCI card or blind flash if something goes wrong)
*checksum not fixed (most certainly not a problem)

Test at your own risk:
http://rapidshare.de/files/38011915/..._vmod.bin.html

EDIT: Clock lock at 862mhz core

I tested this BIOS, it worked, i could go from 760 to 795, but why can't it go higher?


EDIT: Also, is it normal for the thermal sensor to read 45 idle and 60 load? without any modifications to the card!

[ChromeGunner]

Do not use this bios, i flashed my card to it and when i did the reboot Catalyst control would not work at all and Windows found a new pci device, so i installed Catalyst control again but windows kep on saying "Found new hardwar Pci Device" everytime i booted the pc, plus there was no diference on how high i could overclock, so i went back to my old bios.

Gunner

[alexio]

Do not use this bios, i flashed my card to it and when i did the reboot Catalyst control would not work at all and Windows found a new pci device, so i installed Catalyst control again but windows kep on saying "Found new hardwar Pci Device" everytime i booted the pc, plus there was no diference on how high i could overclock, so i went back to my old bios.

Gunner

Might have to do with the device ID being unreadable without the checksum fix. This should be fixed with the new bios I made.

Thanks for testing anyway

[ChromeGunner]

""http://rapidshare.de/files/38027384/test2.rom.html

Checksum corrected, think it's ok now. Device id = HD3870 NEED TESTERS""""

that is the one i used and you said the checksum was fixed....just a heads up

[alexio]

""http://rapidshare.de/files/38027384/test2.rom.html

Checksum corrected, think it's ok now. Device id = HD3870 NEED TESTERS""""

that is the one i used and you said the checksum was fixed....just a heads up

Did you flash without the -f flag? If not then can you test if it works without the -f flag? If it works I'm sure that at least the checksum is correct now