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Radeon HD 4850 Voltmods

Brainless

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Never try pencil mod without multimeter. It's suicide for your video card.
I noticed that on my card, changing voltage through bios does not give any effect.
 

Gregsm

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Fine, I just bought this one...
I didnt see any 2,5 or 3,5 accuracy mentioned on the package though, so dunno whats this. I hope it has all necessary measurements.
So what now? what to put it on?
 

Wile E

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Gregsm

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No, I mean the switcher :)
 

Wile E

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Gregsm

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After 4th try to apply pencil to that thing, I increased just 0.04v. From 1.2 to 1.24 under load. Either my pencil is wrong (some HB2, while I read you suggest B2), or Im not doing this right... I draw vertical lines, from one edge to other, on that little rectangle that pointed with pencil on the pic. Am I supposed to make connection with other point near by? Left or right, like in 2nd mod...

EDIT: I did few more strokes and voltage increased further by 0.02 to 1.26 under load. Perhaps I should try more... Does pencil darkness matters?

EDIT: Ok, I managed to draw 1.35v on load, and I'm testing 800 mhz core for artifacts, with ATITool. Core temp below 56 for more than 5 min. Memory, which is 1130 Mhz, below 72c.
 
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wouldent it be better to get a pure carbon pencil from an art supply store, as thats what pencils are glued carbon sticks.
 

Gregsm

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If I knew what is it... Anyway this works for now. 800 core. Shame that ram cooling so poor.
 
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What bugs me the most is video card makers say there card is the bomb! there card is better than any thing and is the fastest on the market. you have 20 guys telling you there card is good and then you think what do i believe, each card has some thing good if not better than the others
do these card makers really get input from the end user as to what they would like? what works best etc, i have noticed that most people have issues with cooling, ya think the makers would put a better cooler on there top notch card eh.. pity one can not get all the best cards and cannibalise them to make one super duper card with all the mods one can wish for.
who knows what to believe these days so many cards out there eh
 

Gregsm

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Well I opened my 4850 BIOS with Radeon BIOS editor, (BIOS aquired with GPU-Z), and it set 500/750 @ 1.046v, and 500/933 @ 1.084v. I didnt measure with multimeter though. I wonder when does it run 500/933...
Lowest 0.892, and its what I set for idle clocks after pencil mod. Now I just measured with multimeter and got 1.02 idle and 1.362-1.356 load. I guess I should set idle voltage to next setting, 0.930, to be closer to default voltage. But on second thought what does it matter if as soon as something heavy loaded, the card switched to max voltage anyway...
 
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escd101

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Hello all. I have HIS HD 4850 IceQ 4 1GB GDDR3 Card. Card can be o/ced to 680/2100 at stock voltage, but its pretty cold so i decided to make a 1st pencil mod (1.4v) but my card components differs a little from reference. What will happen if i will connect target solder pods directly? I afraid to fry my card :twitch: (this card part is marked with red circle in my attachment)
 

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Wile E

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Hello all. I have HIS HD 4850 IceQ 4 1GB GDDR3 Card. Card can be o/ced to 680/2100 at stock voltage, but its pretty cold so i decided to make a 1st pencil mod (1.4v) but my card components differs a little from reference. What will happen if i will connect target solder pods directly? I afraid to fry my card :twitch: (this card part is marked with red circle in my attachment)
Do not solder any points together like that. It's a surefire way to fry a card.

You can try penciling between the 2 points. Sometimes that will work. But absolutely make sure you have a digital multi meter to confirm voltages.
 

haldir

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Hello all. I have HIS HD 4850 IceQ 4 1GB GDDR3 Card. Card can be o/ced to 680/2100 at stock voltage, but its pretty cold so i decided to make a 1st pencil mod (1.4v) but my card components differs a little from reference. What will happen if i will connect target solder pods directly? I afraid to fry my card :twitch: (this card part is marked with red circle in my attachment)
I have the exact same card and I tried both mods.

First pencil mod doesnt work cause on our card theres no resistor there. So its basicaly an open circuit. Resistance reads something like 90kohm so open circuit.

Second pencil mod WORKS!!!!! The one u have to pencil across the pcb.

Before pencil resistance is about 2.7 kohm.

For me after pencil resistance droppd to about 2.3 kohm and Vgpu at 1.32 idle 1.34 load.

Im at 800 currently and 500 sec of ati testing no artifacts WOOOOT!
 

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Hello guys!! First off, thanks W1zzard for this voltmod guide, this TechPowerUp forum is awsome and a exellent information source even tho my English is crap.(I´m from Sweden)

I would be really,really grateful if anyone of you could provide pictures or something of how/where to pencilmod Sapphire 4850 dual slot (with the blue shorter PCB + different cooling)

This particulary card sells very well here in Sweden, probably in the whole world with it´s low price. So I think there are many of oss who would be grateful for a image/picture of where on the PCB to "pencilmod" and measure ohm + volt.

BR: fark
 
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Phew! im sure glad you guys have bucks to spend on video cards. if ya screw up on the mods and fry ya card in butter and garlic and mushrooms, at least you can buy another one :)
 

dlxmax

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After six pages of discussion over several months, I'm surprised to be the first one here to say:

DON'T DO THE PENCIL MEMORY VOLTAGE MOD!

However, the pencil mod for the GPU is great. It allowed me to get up to 750mhz reliably. My memory was even acceptable with stock volts allowing 1170mhz. But I wanted to give the memory mod a shot and see if I could push it a little further.

So I put a little pencil on the resistor, then used canned air to blow away the excess. Booted up the computer and immediately reached for the multimeter to check the voltage, when the computer shutoff. It didn't even finish posting.

I cut all power, and wiped down the modded resistor with some isopropyl alcohol, then dried it off with canned air. No boot. No power. DEAD.

The horrible part of this story is that this is the second 4850 I've killed with the memory voltage mod. I killed one last week by lazily shading the resistor while the computer was running (total bonehead move). Of course I know better than to do that, I just wasn't thinking. A quick trip to the local service center resulted in a card exchange. But now I've killed the exchanged card. Crap. I don't think the service center will be as nice the second time around since I was just there and they'll remember me. I could wait a few months, but I think I'm going to get a friend to go exchange the card instead. I hope that'll work.
 
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LoL not your day is it :) did it send up smoke rings as it died :)
 

Filu

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Hi @ll,

thanks for this guide, I´ve made the pencil mod and reached 1,31V under load. My Asus HD 4850 works w/o any problems @ 800/1200. I´ve got two questions:

1. Is it possible that if u do the pencil Vmod - the memory OC`bility increases too?? Since I made the pencil mod, I could oc the memory further. Before it wasn´t possible to set 1200 Mhz, but now no problem at all.

2. Does anyone tried to set CCC limit further then 800 Mhz? Rivatuner doesn´t work since Catalyst 8.11

in the end: sorry for my english - I´m german - no... I´m Turk living in Germany ^^

greetz
 

hapek

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This is "SONIC" model. It is with 3-phase power supply (much better that 2-phase on your and my cards).

RAMDAC has nothing with overclocking. It is responsible to send video information to your monitor.

And here are the pictures:




First one is for VGPU, second is for VMEM.
Be very careful when shading this resistors(with yellow border).
I also put small heatsinks over chips with red border. I noticed that when this chips get hotter, voltage also increase and this provoke more load over them( and more heat respectively). Almost fryed my card. VGPU was 1.35V at idle, and after couple of minutes under FurMark, reached over 1.5V.
Hey, it helped me alot as it works fine for me. But my lil problem is i dunno measure points i just noticed much better OC results. Could you post them as well please ?
 

szuma

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Hi.
I have the GIGABYTE R485MC-1GH.



Does anyone know where how to pencil mod this card?

Szuma
 

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After six pages of discussion over several months, I'm surprised to be the first one here to say:

DON'T DO THE PENCIL MEMORY VOLTAGE MOD!

However, the pencil mod for the GPU is great. It allowed me to get up to 750mhz reliably. My memory was even acceptable with stock volts allowing 1170mhz. But I wanted to give the memory mod a shot and see if I could push it a little further.

So I put a little pencil on the resistor, then used canned air to blow away the excess. Booted up the computer and immediately reached for the multimeter to check the voltage, when the computer shutoff. It didn't even finish posting.

I cut all power, and wiped down the modded resistor with some isopropyl alcohol, then dried it off with canned air. No boot. No power. DEAD.

The horrible part of this story is that this is the second 4850 I've killed with the memory voltage mod. I killed one last week by lazily shading the resistor while the computer was running (total bonehead move). Of course I know better than to do that, I just wasn't thinking. A quick trip to the local service center resulted in a card exchange. But now I've killed the exchanged card. Crap. I don't think the service center will be as nice the second time around since I was just there and they'll remember me. I could wait a few months, but I think I'm going to get a friend to go exchange the card instead. I hope that'll work.

Is there any truth to the memory pencil mod not working? I haven't tried it and have put it off for later.
 
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dread_stef

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For anyone that's interested: I think this is where the pencil mod for the Sapphire non reference (blue PCB, round dual slot cooler) card should be applied:
http://img57.imageshack.us/img57/1804/vmodareawm9.jpg

It's at the DVI connectors end of the card, in between the 2 pins that hold the VRM cooler.

I'm not sure though, and I haven't found the right points to measure yet. If anyone has a closeup of the vGPU measurement points that'd be great. I'm a bit psyched because this is my second card, the first one lasted about half an hour (no mods, no overclock), it just died on me.
Also, I've heard someone say that the VRM's on this card cannot cope with 1.058v. Does anyone have any experience with this?
 
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Is there any truth to the memory pencil mod not working? I haven't tried it and have put it off for later.
Yes, I did it on my card, and it wouldn't come on. Thought I bricked the card, but I erased the pencil and it started working fine again :)