ATI 3850/3870 Voltmod thread

**kup** · 03-11-2008, 02:27 PM

Hard mod or pencil mod? If it's pencil I'd advise having a close look for any loose graphite causing problems as this is the second time I've read about a 3870 just dying. The guy cleaned the card from top to bottom with cleaning alcohol and it worked again...

**Eldonko** · 03-11-2008, 02:46 PM

Hard mod. But cleaning is worth a try

**Jimbo Mahoney** · 03-12-2008, 11:55 AM

My attempt at defeating OCP didn't work, although the card is still alive even without the resistor I removed

**MagnumMan** · 03-12-2008, 11:59 AM

Has anyone found that they need to dial down the overclock once Crossfire is enabled? I had one card running at 985/1300 with 1.56V on the GPU with a simple pencil mod (2D is 1.4V). Then I added a second card fixed at 1.4V 2D/3D at 950/1226 and it was not stable. I had to bring the first card down.

I have a better soldering station on the way and I am ordering some trimmers today. I'm only going to go for a simple GPU voltmod on a trimmer at this point. The memory seems to clock just fine at stock voltage (and ashamedly I have not been able to find the picture I need to locate the vMEM position, and I went through a lot of these posts, or I might try it as I ordered 10 trimmers from DigiKey (part 3006P-104LF-ND).

Does anybody have a solution for displaying the card's current voltage on an LCD or numerical readout with blue numbers? Something I could affix to the card so it is visible through the side window? I saw this somewhere...

http://www.amiaworld.net/qq_light.jpg
http://www.amiaworld.net/qq_dark.jpg

**STaRGaZeR** · 03-12-2008, 03:54 PM

Hey guys, i don't know if this has been already posted in this thread. I just picked up an ASUS 3870, and it doesn't follow reference design. Here are some photos, any chance of pencil mod?

If you need bigger photos or something more centered/focused, let me know

Thanks in advance!

**slugzkea** · 03-12-2008, 06:30 PM

omg....guys...

I tried the resistor pencil mod, and i was with little luck.

I then tried the german pencil mod, which got me up to 1.37v, but that's not enough.

So i went ape

and combined both pencil mods, which got me up to 1.62v

At first, i was scared to keep the system booted, since i don't have any way to see the temps until i get into windows. But i took the risk.

I got into windows, and temps were fine, load was in the 50's, thanks to my 900 case.

I am now testing benchies at 1ghz core, 1301 mem.

I'll post screenies once i'm done.

**slugzkea** · 03-12-2008, 06:51 PM

Originally Posted by slugzkea

omg....guys...

I tried the resistor pencil mod, and i was with little luck.

I then tried the german pencil mod, which got me up to 1.37v, but that's not enough.

So i went ape

and combined both pencil mods, which got me up to 1.62v

At first, i was scared to keep the system booted, since i don't have any way to see the temps until i get into windows. But i took the risk.

I got into windows, and temps were fine, load was in the 50's, thanks to my 900 case.

I am now testing benchies at 1ghz core, 1301 mem.

I'll post screenies once i'm done.

Okay everything seems okay so far.

I had to clock down the memory to 1236, Going to attempt the vmem pencil mod another day.

For now, 3dmark06 scores is around 13,700's. Not bad?

My goal is to be in the 14k, cpu score is around 3950's

**Clint** · 03-12-2008, 08:55 PM

Originally Posted by slugzkea

omg....guys...

I tried the resistor pencil mod, and i was with little luck.

I then tried the german pencil mod, which got me up to 1.37v, but that's not enough.

So i went ape

and combined both pencil mods, which got me up to 1.62v

At first, i was scared to keep the system booted, since i don't have any way to see the temps until i get into windows. But i took the risk.

I got into windows, and temps were fine, load was in the 50's, thanks to my 900 case.

I am now testing benchies at 1ghz core, 1301 mem.

I'll post screenies once i'm done.

Could you please show me the linky or the actual German mod?

Thanks!

**Eldonko** · 03-13-2008, 07:52 AM

Yeah, what is a german pencil mod?

**largon** · 03-13-2008, 10:01 AM

Originally Posted by STaRGaZeR

Hey guys, i don't know if this has been already posted in this thread. I just picked up an ASUS 3870, and it doesn't follow reference design. Here are some photos, any chance of pencil mod?

(...)

If you need bigger photos or something more centered/focused, let me know

Find where the pin marked with number 13 leads on the bigger chip. Also, a better shot of the cropped area with good lighting would be nice.

Measure resistance to ground from these locations:
Pin#7 on the smaller chip (AT-9J?)
Pin#13 on the larger chip (BD-9J?)

Click image for larger version.

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**ante_ante** · 03-13-2008, 10:40 AM

I have a Powercolor HD3870 DDR3 card, is it same v-mods or not ??

**STaRGaZeR** · 03-13-2008, 11:43 AM

Originally Posted by largon

Find where the pin marked with number 13 leads on the bigger chip. Also, a better shot of the cropped area with good lighting would be nice.

Measure resistance to ground from these locations:
Pin#7 on the smaller chip (AT-9J?)
Pin#13 on the larger chip (BD-9J?)

Tomorrow I will take better photos and do the measurements. For now this is that photo but this time not resized. Seems that pin 13 is not connected to anything?

**largon** · 03-13-2008, 12:49 PM

STaRGaZeR,
The pin is probably connected to a PCB-via that leads to the backside.

**Eldonko** · 03-13-2008, 01:56 PM

Yeah you need good light and macro shot to see the traces on the pcb so you can map what goes where.

**STaRGaZeR** · 03-15-2008, 08:20 AM

Bad news guys. Yesterday after taking the required photos the card destroyed itself when booting into Windows. I heard a big BANG! and the screen went black. Looking at the card there is no visible damage, but this thing is completely dead. I will look for a replacement, and RMA time... cards self-blowing without any kind of stress sucks

Thanks for your help largon and company though, much appreciated

**MagnumMan** · 03-15-2008, 11:37 AM

Ouch sorry to hear that.
I posted a question in another thread:
http://www.xtremesystems.org/forums/...d.php?t=180671
Any ideas?

**HDed** · 03-16-2008, 09:34 AM

sup guys
how much voltage is safe for 24/7 for the HD3850 core (1.55??)

**775911** · 03-16-2008, 10:03 AM

Depends on the cooling I think. 1.4v on air is safe and water much higher I think

**HDed** · 03-16-2008, 10:07 AM

Originally Posted by 775911

Depends on the cooling I think. 1.4v on air is safe and water much higher I think

i guess it`s not gonna be stock cooling

i just wanna hit 1Ghz core clock
my card is HIS HD3850 256mb

**775911** · 03-16-2008, 10:30 AM

just ? 1ghz sounds alot to me

I bought my 3850 with a hard vmod but Im not sure how much I have to turn the screw to adjust voltage slightly, is it generally clockwise for more volts

temps are in the 70's which seems good to me

**HDed** · 03-16-2008, 10:34 AM

Originally Posted by 775911

just ? 1ghz sounds alot to me

I bought my 3850 with a hard vmod but Im not sure how much I have to turn the screw to adjust voltage slightly, is it generally clockwise for more volts

temps are in the 70's which seems good to me

i guess it depends on ur cooling and incase air flow

**ceemic** · 03-16-2008, 10:47 AM

My Vmoded HD3870 runs 24/7 1,477V 2D and 1,519V 3D

Aircooling...

1GHz@HD3850 24/7 use is pretty impossible...

**HDed** · 03-16-2008, 11:01 AM

Originally Posted by ceemic

My Vmoded HD3870 runs 24/7 1,477V 2D and 1,519V 3D

Aircooling...

1GHz@HD3850 24/7 use is pretty impossible...

why not they are using the same core just different memory

**ceemic** · 03-16-2008, 11:10 AM

HDed, if You look HWBOT, You'll see, that only few 3850's can do over 1000MHz. And thats bechmarking probably with higher voltage and better cooling.

**kup** · 03-16-2008, 11:10 AM

Originally Posted by HDed

why not they are using the same core just different memory

The 3850 Cores are speed binned lower, they're literally not as good as the 3870 Cores.

Thread: ATI 3850/3870 Voltmod thread

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