ATI 3850/3870 Voltmod thread

[victorbr]

are you fully alright man?? i dont have cash to buy another card dude uhuauhuah

[Random Murderer]

are you fully alright man?? i dont have cash to buy another card dude uhuauhuah

yep, completely sure. if you're wary, you can wait for others to confirm what i said and it won't hurt my feelings one bit.

[victorbr]

yep, completely sure. if you're wary, you can wait for others to confirm what i said and it won't hurt my feelings one bit.

thx friend,i don't wanna hurt your feeling ,i am just having a bit of caution with my vga ..i don't wanna fry it

[Random Murderer]

thx friend,i don't wanna hurt your feeling ,i am just having a bit of caution with my vga ..i don't wanna fry it

hey, no problem, i completely understand.
the thing about pencil mods is that if your card blows up, erase the mod and rma it! while some may call this irresponsible or unethical, i believe that since we paid for it we should be able to rma it. the big manufacturers have money to replace it, we don't.

[Jaan]

Got Gigabyte HD3850 to mod- it has non-reference pcb with Nexsen PWM controllers on it.
Card has Zalman cooler and blue pcb, but I think same mods can be used for other cards with same PWM chip.
Vgu mods- I measured 10K resistance between GND and FB pin.
This is without mods!
Red line is connected to FB pin and any point of it can be used for "fooling" feedback voltage to chip.


Vmem mods- same story.


Actual mods on extra pcb:

and schematic diagram:

Voltage monitoring poins are knows already I think.
Mods working fine, Vgpu is limited at ca.1,75V with extra resistance on Vgpu, if you need more, use resistor with lower resistance.

[Random Murderer]

Got Gigabyte HD3850 to mod- it has non-reference pcb with Nexsen PWM controllers on it.
Card has Zalman cooler and blue pcb, but I think same mods can be used for other cards with same PWM chip.
Vgu mods- I measured 10K resistance between GND and FB pin.
This is without mods!
Red line is connected to FB pin and any point of it can be used for "fooling" feedback voltage to chip.


Vmem mods- same story.


Actual mods on extra pcb:

and schematic diagram:

Voltage monitoring poins are knows already I think.
Mods working fine, Vgpu is limited at ca.1,75V with extra resistance on Vgpu, if you need more, use resistor with lower resistance.

that's some ace-modding there!
NICE WORK!

[Viilutaja]

I am that lucky guy who got this mod on my Gigabyte HD 3850 512mb card.
Right now 860mhz on core is max what i get out with this "locked" bios. Without that mod and 1,256 v i got only 805 mhz max stable under benching. Memory is Hynix 1.4ns and right now i could get stable bench clocks with RTuner 1044mhz with stock vmem.

3DMark06 skore is 13568

http://service.futuremark.com/compare?3dm06=5461767
Not bad
Now in need of a good bios mod. So can go for 1000mhz.
And about temps. I have default Zalman cu700, bench temps i saw in load with RT monitoring were 81C. But those were with very high vcore, wich i just put on, knowing that those will be enough to pass with 860 core speed. Now try to lower them to optimize.

Thanks Jaan!