How-to: Pencil mod your HD 3870!

[KurosakiIchigo]

Using CRABE Radeon BIOS editor to up the VCore, does it give the same results as this pencil mod?

I found the article that uses CRABE here

any pros and cons using just a bios mod to up the VCore?

Thanks, Mark - OC noob

you cannot modify Vcore with the bios , you have to set it up with an hardware mod

 

[Dr. Spankenstein]

Using CRABE Radeon BIOS editor to up the VCore, does it give the same results as this pencil mod?

I found the article that uses CRABE here

any pros and cons using just a bios mod to up the VCore?

Thanks, Mark - OC noob

I understand what your suggesting.

Try to make all clocks work @ 3D speeds and voltages since he is trying to bypass the resistor. It could work, IF you were able to flash a non-booting card. Not sure on that one.

Do you have another PCI-e video card you could use while you flash the dead one?

 

[sleepsus]

I understand what your suggesting.

Try to make all clocks work @ 3D speeds and voltages since he is trying to bypass the resistor. It could work, IF you were able to flash a non-booting card. Not sure on that one.

Do you have another PCI-e video card you could use while you flash the dead one?

I've actually tried it on my not-dead Palit HD 3850 Super (512MB DDR3)
I did get it to 810/1125, but it was unstable, so I'm not sure if this could be because the VCore setting in CRABE doesnt really have any effect.

BTW techPowerUp also has a bios editor that features VCore adjustments here

 

[Random Murderer]

Trimmer set to 96 Kohm (measured with the tester)

is it a single or multi turn pot?

 

[KurosakiIchigo]

is it a single or multi turn pot?

single

 

[Deleted member 24505]

You need a 15 or 22 turn 100kohm cermet trimmer.
Like this-

You cannot get the resistance fine enough on that type.

On my 3850,the resistances are as follows.

61.3kohm=1.34vgpu
61.0kohm=1.39vgpu

If this helps.

 

[Random Murderer]

single

as tigger said, you need at least a 15 turn pot.

 

[KurosakiIchigo]

as tigger said, you need at least a 15 turn pot.

sure ? if so , i will buy one of this

 

[Random Murderer]

sure ? if so , i will buy one of this

do you have a link?

 

[sleepsus]

you cannot modify Vcore with the bios , you have to set it up with an hardware mod

Sorry, I'm confused if I should do the pencil mod or just the bios mod to up the VCore ?

I did just the bios mod this morning on my HD3850 and ...

Here is a screenshot of AMD Overdrive reporting 1.375V on the VCore while running Gears Of War in the background:

http://img.photobucket.com/albums/v244/sleepsus/sleepsusSS-1.jpg

Is it correct? I'm not aware of any other tool that monitors GPU VCores?

 

[sleepsus]

It's also strange that Everest and GPU-Z report slightly lower speed values compared to AMD Overdrive.

AMD Overdrive reports more accurately the actual values i used in the bios editor.

My bios attached if anyone's interested, - From a Palit HD 3850 Super (512M/DDR3), extracted via GPU-Z and edited with CRABE

 

[Random Murderer]

It's also strange that Everest and GPU-Z report slightly lower speed values compared to AMD Overdrive.

AMD Overdrive reports more accurately the actual values i used in the bios editor.

My bios attached if anyone's interested, - From a Palit HD 3850 Super (512M/DDR3), extracted via GPU-Z and edited with CRABE

last i heard, there is no way to raise the voltage through bios software, even though most cards support it.
as far as i know the only way to raise voltage is to tinker with the hardware in some way, such as a pencil mod or the trimmer mod.

 

[sleepsus]

last i heard, there is no way to raise the voltage through bios software, even though most cards support it.
as far as i know the only way to raise voltage is to tinker with the hardware in some way, such as a pencil mod or the trimmer mod.

I see now what you guys mean ... bios may support it but the hardware may not actually implement the voltages set in bios ...

I'll need to find myself a DMM and know for sure!

Anyone figured out where the read point on a 3850 is?

 

[sneekypeet]

I see now what you guys mean ... bios may support it but the hardware may not actually implement the voltages set in bios ...

I'll need to find myself a DMM and know for sure!

Anyone figured out where the read point on a 3850 is?

what manufacturer of HD3850?

 

[sleepsus]

what manufacturer of HD3850?

It's from Palit

 

[sneekypeet]

I assume the Palit is on a non reference PCB. Wait for Random tho on that one. Im not really sure, based on my assumption!

 

[Deleted member 24505]

Can you post a pic of the back of your card sleepsus please?

 

[sleepsus]

will do, once I get home from work

 

[Random Murderer]

I assume the Palit is on a non reference PCB. Wait for Random tho on that one. Im not really sure, based on my assumption!

although i can't say this for sure, palit has never made a reference 3870. if they have, i've haven't seen it.
in the case that it is not a reference pcb, you'll need to do a bit of detective work(we'll help you) to find out where the measure point is. there is only so much we can figure out without actually having the card in our hands.

 

[KurosakiIchigo]

do you have a link?

Link Trimmer

 

[Dr. Spankenstein]

For mounting purposes, this would be better!

 

[KurosakiIchigo]

so maybe the problem is the trimmer , because reach 96kohm and not 100kohm ?

 

[Deleted member 24505]

No its not that it does not reach 100kohms.Its because the adjustment on the old one is too coarse.Either of them two linked will be fine.I use the type you first linked.

The reason for setting the trimmer to max resistance when you fit it is so you dont blow your card with too much voltage for the gpu.As an example,mmy trimmer is set to 61.0kohms which gives the gpu 1.39v.

Imagine what would happen to your card if you fitted the trimmer set at 50kohms or less.

 

[KurosakiIchigo]

now i want only that the card boot...

 

[Dr. Spankenstein]

He has stated that he measured resistance @ 96kohm. This should be fine. It would just operate close to stock voltages.

Something else has happened. Either the PCB has been damaged (by either the physical breaking of the resistor OR the ham-fisted soldering job.

I'm still leaning towards soldering at the leg of the IC to bypass the fried traces. But that's just me...