Pencil mod 3850

Goldfingers · 8 Feb 2008 at 15:49

Quick one, has anyone got any guides on how to do this - where to mark, what HB to use, how to get different voltages and what is safe etc. ?

I heard the pcb is a little different from the 3870 so i don't think the 3870 guides apply

waso_dude · 8 Feb 2008 at 15:58

gurusan did his had to over 1ghz on the core iirc.

Might be worth giving him a email.

Goldfingers · 8 Feb 2008 at 16:05

waso_dude said:
gurusan did his had to over 1ghz on the core iirc.

Might be worth giving him a email.

call me a noob ...but i'm not sure how

Normally there is a 'pm' option but here nothing

Trunks9486 · 8 Feb 2008 at 18:06

I am interested in this as well... at least if its safe enough

Goldfingers · 8 Feb 2008 at 18:45

Trunks9486 said:
I am interested in this as well... at least if its safe enough

Well there's always the risk someone could get electricuted.

You were talking about sending a PM right

Goldfingers · 8 Feb 2008 at 21:24

Be . Yuu . eMM . Pee

muon · 8 Feb 2008 at 21:34

Read through this thread.

http://forums.techpowerup.com/showthread.php?t=48544

The 3870 mod is the same as the 3850 one unless you have a non reference PCB layout.

i can also if you wish, mod your BIOS to any voltage upto 1.327v and pick any 2d/3dclocks provided its all stable.

gurusan · 8 Feb 2008 at 21:44

Which 3850 do you have in particular?

Trunks9486 · 8 Feb 2008 at 21:46

I have the Powercolor 512 MB variant... Not sure if its a custom PCB, it has a custom zerotherm cooler on it though.

CCC limits the clock to 730/950 and from some basic testing its not stable even at that with stock volts.

Goldfingers · 8 Feb 2008 at 21:46

Gonna get the power colour 3850 extreme.

Gurusan i found some of your posts in the xtreme systems thread, showing where to measure Vgpu aswell.

Just wondering if you have any advice doing the mod? Is it a case of wack a few strokes on and then test the voltage?

Got any info on the Vmem mod?

gurusan · 8 Feb 2008 at 21:50

This is a pic I took of my card (it's the same powercolor pcs version)

The circled resistor is the one to shade....and the other 2 circled points are vGPU measure points. Just touch the + probe to one of the points and the - wire to any ground to measure vGPU.

Goldfingers · 8 Feb 2008 at 21:52

Thanks a bunch

Just wondering about the Vmem mod now? How do i put more volts through the mem?

gurusan · 8 Feb 2008 at 21:52

Goldfingers said:
Gonna get the power colour 3850 extreme.

Gurusan i found some of your posts in the xtreme systems thread, showing where to measure Vgpu aswell.

Just wondering if you have any advice doing the mod? Is it a case of wack a few strokes on and then test the voltage?

Got any info on the Vmem mod?

As far as advice...you've basically got it....stroke it a few times until the resistance goes down a bit (i seem to recall stock being 2.6kOhm and 2.4kish being around 1.45-1.5v) and measure the vGPU

And for Vmem...you should be able to hit 1098 on stock vmem...I raised it to 2.2v from 2.1 and got a whole 25mhz boost to 1125. I would just leave the vmem @ stock

Trunks9486 · 8 Feb 2008 at 21:55

What kind of Pencil should be used?

Goldfingers · 8 Feb 2008 at 21:59

Trunks9486 said:
What kind of Pencil should be used?

4H if possible i think.

So should i measure the voltage at the points or the resistance, if the resistance how?

I know this sounds petty, but if you've got any info on the vmem mod please post it - i wanna push this to it's limit.

gurusan · 8 Feb 2008 at 21:59

i just used a HB 2 pencil. Shade it then blow on it a little to get rid of any pencil dust...then measure vGPU. Once your desired clock is reached then I advise putting a piece of tape over the resistor very carefully to prevent the pencil from rubbing off.

gurusan · 8 Feb 2008 at 22:08

Goldfingers said:
4H if possible i think.

So should i measure the voltage at the points or the resistance, if the resistance how?

I know this sounds petty, but if you've got any info on the vmem mod please post it - i wanna push this to it's limit.

Measure the voltage at the circled points. and NEVER measure resistance when the card is switched on!

As for memory, if you really want to adjust your vdimm then you shade this resistor marked in green

The marked spots are vDIMM measure points and you can use the ground on the PCI-E plug as the ground for your meter.

gurusan · 8 Feb 2008 at 22:08

also remember if you blow up your card don't blame me

Goldfingers · 8 Feb 2008 at 22:23

Cool, and you measure Vgpu with the pc turned on?

gurusan · 8 Feb 2008 at 22:25

Well yeah, otherwise there wouldn't be any voltage going through it