Radeon HD 4850 Voltmods

[W1zzard]

[page=Introduction & Overview]
Introduction
This voltmod applies to all HD 4850 series cards using PCB #B50131-00.

The HD 4850 supports very limited voltage control via BIOS or software, only up to 1.20V

Disclaimer:
Performing these voltmods will void any and all warranties your video card may have.
You - and only you - are responsible for any damage caused indirectly (or directly) by these modifications.

Overview
http://www.techpowerup.com/articles/151/images/overview_small.jpg (http://www.techpowerup.com/articles/151/images/overview.jpg)

[page=GPU Voltage Mod]
GPU Voltage Mod (soldering)
http://www.techpowerup.com/articles/151/images/vddc_solder.jpg

GPU Voltage Mod (pencil)
You have to do only one of those mods, depending on the voltage you want to achieve.

http://www.techpowerup.com/articles/151/images/vddc_pencil1.jpg
This first voltage mod is easy to do but will not give you much more than about 1.4V on VDDC.

http://www.techpowerup.com/articles/151/images/vddc_pencil2.jpg
If you need more than 1.4V you should do above voltmod. Please note that you have to paint on the PCB between the two solder dots. Since this is more difficult we recommend the first pencil mod for smaller voltage increases.

[page=Memory Voltage Mod]
Memory Voltage Mod (soldering)
http://www.techpowerup.com/articles/151/images/mvddc_solder.jpg

Memory Voltage Mod (pencil)
http://www.techpowerup.com/articles/151/images/mvddc_pencil.jpg

[boogerlad]

wizzard, is the smd capacitor that you are showing on the vgpu voltage mod ground?

[Scrizz]

thx

[newtekie1]

How are the overclocking results with these mods? Does it help the poor overclocking issues any?

[W1zzard]

the big yellow cap on the left side of the vgpu mod is gnd

[Kaleid]

I'm thinking about doing the pencil mod (for the first time since the days of Duron)
I'd like to have a bit more information if possible.

1. What kind of pen to use?
2. How much do you shade with the pen?
2.5 As I've understood the more shade the less resistance and thus higher voltage. Correct?
3. Do I need a Digital Multimeter to measure the VDC+resistance (I'd rather not at all)
4. Do I need to download a new firmware to the card? If so, then where? (Ordered a Sapphire 4850)

Thank you for your hard work :)

[calvary1980]

#2 pencil and a multimeter.

- Christine

[Kaleid]

Thanks for the replies. I guess I have to chicken out then... :(

[scamps]

Thank you, W1zzard!

Is there already any software to manipulate the VGPU under Windows when I have done this Voltmod? Or is it necessary to flash the bios for each alteration?

[HeLLscream]

Thank you so much.I searched a lot this.

[ViciousXUSMC]

Just connect the two solder dots the pencil point is pointing at to short that out? Seems easy enough, but was wondering why only one picture actually shows a line drawn between the points? I guess it has something to do with the "paint"?

Anyways wonderful guide!

[W1zzard]

the line in the picture is to clarify that you have to pencil between the points across the pcb. usually you pencil on a component like a resistor

[ViciousXUSMC]

Thats what I thought, thanks for clerifing.

Im dead in the water right now with both my 4850's I think a bad bios flash, or corrupted drivers. O a combo of both the bios flash made the drivers go fubar.

[DavyGT]

I know that this is an ubernoob question, but how do I measure the VGPU voltage? I'm guessing it doesn't matter where the + and - leads go, just at one any one of the points. Am I correct?
Can someone also post some benches of their new overclocks as well?

[ShadowFold]

What kind of pencil would I need to do a pencil mod?

[DavyGT]

What kind of pencil would I need to do a pencil mod?

A good 2B or 4B pencil. I used my Faber Castell 2B pencil. Strangely enough, my 4B pencil doesn't decrease resistance at all, only adds to it, so always have an alternative at hand.

[W1zzard]

I know that this is an ubernoob question, but how do I measure the VGPU voltage? I'm guessing it doesn't matter where the + and - leads go, just at one any one of the points. Am I correct?
Can someone also post some benches of their new overclocks as well?

you put the red probe to the measure point and the black probe to any ground which could be case metal, molex connector black cable, pcie power plug gnd or a million other spots. the grounds are all connected with each other

[boogerlad]

another uber noob question: how much wattage for the resistor? i found various 100k ohm variable resistors, but they come in different wattages.

[LifeOnMars]

Any ideas on how long the pencil would stay on there for once modded? Never done this before and don't want to have to keep applying every two weeks, thanks.

[LifeOnMars]

so for that first pencil mod are we putting it on top of that one already filled or the empty one next to it?

[LifeOnMars]

no worries, all sorted. Now at 790/1180 stable :) £117 quid well spent

[yanahs]

hi guys.. quick question if I use the first pencil mod.. which only alows 1.4 volts (no more).. does that mean i can actually just pencil as much as I want without worrying overvoltage? (no need a dmm)?

[tomcug]

Yes, I think you can't kill your card with the first pencil mod, but everything depends on your cooling. If you have a good aftermarket cooler, you don't have to worry about anything. But if I were you, I wouldn't do this without DMM.

[yanahs]

I got an accelero on it and i get 38 ide 45 load.. what do you think sufficient?

[tomcug]

If you have Accelero S1 on it, then you can try that pencil mod. But remember to check temperatures all the time, especially #2.

[yanahs]

great.. thanx bro.. btw you got you4 4850 @850 on which mod? pencil or soldered

[Scrizz]

I got 850 on mine with pencil :rolleyes:
:D

[yanahs]

1.4 nice 850.. that means you only had to do the first pencil mod.? dude theres 3 measuring point why 3 is it like point one idel, point 2 load, point 3 i dont know.. or do we only have to read measure one of them?

[tomcug]

I overclocked my card to 850MHz with first pencil mod (1,38V). It won't make any difference which one of measuring points you'll use.

[yanahs]

ok thanx guyz will post results

[yanahs]

I've peciled my 4850 and I got it running up to 825/1100 but when I edit the bios to 850/1100 gpuz reports 825/1100 any ideas?
another thing is it possible to run 4850 x fire with a 500 watt pure psu?

[ViciousXUSMC]

I've peciled my 4850 and I got it running up to 825/1100 but when I edit the bios to 850/1100 gpuz reports 825/1100 any ideas?
another thing is it possible to run 4850 x fire with a 500 watt pure psu?

A 500w PSU would be pushing the limits severely I wouldn't attempt it especially with overclocks and volt mods. Something like a PC P&C Turbo SLI 510 would probably be fine, but your standard run of the mill 500w is gonna fall short.

[tomcug]

Really nice results :) If you want to overclock your card more, you can use AMD GPU Clock Tool instead of editing BIOS.

[yanahs]

Really nice results :) If you want to overclock your card more, you can use AMD GPU Clock Tool instead of editing BIOS.

I'll check it out.. but that means i've gotta do the other mod? i cant stick it with the current mod?

[tomcug]

Yes, you can stick with the first mod.

[yanahs]

is there an alternative to using pencil like a hair of wire which i could just tape on it? to reduce risk of degradation?

[me_martin]

Hi all, I just did the pencil mod #1 and i gott 1,495v, I did not expect that.
I used this for the mod : http://www.kemo-electronic.de/de/zubehoer/l100/index.htm
This is the english manual: http://www.kemo-electronic.eu/datasheet/l100.pdf
Is that substance to pure or what? Because 1,495v is way to high for my cooler.

[yanahs]

1.495 pretty big jump :) so what speeds are you hitting?

[yanahs]

@ tomcug
I've downloaded amd clock tool.. tried it but it wouldn't let me pas 750.. any ideas?

[tomcug]

I've never had such problems with this tool. Post a screenshot, so I'll be able to help you.

[me_martin]

1.495 pretty big jump :) so what speeds are you hitting?

I didnt max the card but I did get up to 917MHz :rockout:
But unfortunately I had to remove the mod because of the temp :ohwell:

[sydbod]

@ tomcug
I've downloaded amd clock tool.. tried it but it wouldn't let me pas 750.. any ideas?

I believe reading that ATI/AMD have messed up the clock multiplier the same way as they did with the HD3xxx series so that one can not go higher than 750MHz.
If this is true, then the settings from around 830MHz should be OK again.

Can anyone confirm this information?

[mrg666]

Just stopped by to say thanks for the Vmod guide, bios file, and bios editor. I did the first pencil VGPU mod with my Visiontek 4850, flashed with newer version Powercolor bios, edited with RBE.

Stock Overclocked
Clocks 625/993 800/1100
VGPU ~1.1v ~1.26v
Load temp 48C 55C w/ Accelero S1+120mm_1500RPM_fan
Crysis GPU 33fps 39fps 15 loops, all high, 0AA
bench

Thanks again !!!!

[mYrAn]

Hi, i was just wondering how you can count what voltage you have? Ive done the 2nd pencil mod, the one where you draw on the PCB, and i went from 5.12 to about 4. My multimeter always jumps from like 1.3 to 1.4, so i dont know my exact voltage. So, is there a way to calculate what voltage my core is getting by having the ohm? And how high voltage is considered safe? Thanks in advance!

[me_martin]

I did the pencilmod #1 with a B2 pencil this time and got 820MHz on 1.25~1.26volt on the GPU.
My load temp is 42C and Idel is 35C :D
Just whants to thanks for this mod, nice work:)

[yanahs]

what was your temps before with 1.495v? that L100 stuff is pretty good huh? chemical store or do drug stores have em?

[yanahs]

just to make sure.. this first mod cant provide egough juice cannot kill my card right.. so it safe to say that I can use something with zero resitance on it?

[W1zzard]

just to make sure.. this first mod cant provide egough juice cannot kill my card right.. so it safe to say that I can use something with zero resitance on it?

yes if your resistance is too low, the voltage will go WAY high and WILL kill the card

[W1zzard]

Hi, i was just wondering how you can count what voltage you have? Ive done the 2nd pencil mod, the one where you draw on the PCB, and i went from 5.12 to about 4. My multimeter always jumps from like 1.3 to 1.4, so i dont know my exact voltage. So, is there a way to calculate what voltage my core is getting by having the ohm? And how high voltage is considered safe? Thanks in advance!

buy a better multimeter :) it's like $5

[cp#]

just to make sure.. this first mod cant provide egough juice cannot kill my card right.. so it safe to say that I can use something with zero resitance on it?

Show me something with zero resistance, please :roll:


I don't believe the people with 42-45C load temps. What cooler are you using? Please prove me wrong. I max out at 55C running the ATI Tool scanner with an Accelero S1

[W1zzard]

Show me something with zero resistance, please :roll:

he's probably talking about a wire which is almost no resistance, it will still your kill your card.

[yanahs]

yes if your resistance is too low, the voltage will go WAY high and WILL kill the card

so if i use a single piece of wire there is still the risk of killing my card with the first mod? right now i'm getting 1.3v.. any chance i can safely boost it up ?with the first mod?

[yanahs]

I don't believe the people with 42-45C load temps. What cooler are you using? Please prove me wrong. I max out at 55C running the ATI Tool scanner with an Accelero S1[/QUOTE]

Im using an Accelero S1 tied two 12cm fans on them.. when i dont use the fans it goes up to 60c.. i only use rthdrblt to test load up my gpu though..

http://www.freeimagehosting.net/uploads/72c1fe9f88.jpg (http://www.freeimagehosting.net/)

[W1zzard]

so if i use a single piece of wire there is still the risk of killing my card with the first mod? right now i'm getting 1.3v.. any chance i can safely boost it up ?with the first mod?

you need to use a resistor as instructed. of course you can have wires leading to each end of the resistor (duh?).

[me_martin]

what was your temps before with 1.495v? that L100 stuff is pretty good huh? chemical store or do drug stores have em?

In load my temp was like 80~85C and i think thats to high :S
Presumably the chemical store will have it.

[yanahs]

thanx wizzard

[yanahs]

In load my temp was like 80~85C and i think thats to high :S
Presumably the chemical store will have it.

wow that is pretty hot.. and that with aftermarket coolers?

[kingkongtol]

what the safest temps degree?, im almost 60C, with just pencilmod @750/1175
and, i dont know why my memclock can go higher, beside im just doing vgpu mod, and not vmem mod...

[yanahs]

@kingkongtol
I'm not sure about the safest max limit temp.. but i read somewhere that these 4series may run upto 90c to 100c?? but i like to keep mine under 70..

my mem gave me artifacts @ 1150 (during 3dmark06 / cpu test only) when i went down to 1100.. arties were gone..

cheers bro :)

[me_martin]

wow that is pretty hot.. and that with aftermarket coolers?

I got an Accelero S1 R.2 with two 120mm Noctua fans on it, but it couldn't cool down the GUP enough at 1.495v (thats my opinion :P)

[quasar923]

why do i need a multi reader? and if i really really need one where can i get one and for how much?

[W1zzard]

you mean a multimeter? any cheap $10 one should do. you need 3.5 digits, 2.5 digits is not accurate enough

[DJSUB]

i'm completely noob with this.
i just want to ask what settings to use in the digital multimeter to measure the voltage?
i already killed 2pcs. 4850 because of the pencil modding without a multimeter :(

how can i measure the idle & load voltage of the card?
is it safe to measure the voltage while benching or doing some stability test to get the load voltage?

sorry for my bad english :D

thanks! :)

[Drizzt5]

I'm preparing to pencil mod my 4850, I just got done doing a bios flash. I can't clock any higher then I could before (I think I can clock lower) and an unusal thing happened. On load i used my DMM and it said that there was 1.3v's going through the vgpu....

All i did was flash the bios ? I don't think it's suppoused to go that high?

Did I measure it wrong? If I don't have something properly grounded will it measure higher then it's suppoused to? And I'm still on the stock cooler for the moment (my s1 is sitting right next to me, ready to go) and my temps seem good. I don't think I'm measuirng correctly. But I tried all 3 of the vgpu spots that I know of.


Anyone have any suggestions?


P.S. my card is the Asus 4850, and I flashed it using this bios.

3. Asus HD4850 Light Overclocked. DF Core 700MHz Mem 1100MHz Auto Cool Fan.
GPU Core upper Limit 1200MHz
Memory Upper limit 1400MHz
Vcore DF 1.12V

Asus HD4850 Light Overclocked (http://thienloipc.com/leonarderman/hd4800bios/ASUS.4850.PCIe.512MB.Rev.01.bin)


I'm also using this DMM
http://img.photobucket.com/albums/v521/jazzarmando/DSC02911.jpg

And i set it to the 2 for DCV (right side of the dial) :/ If thats the wrong spot then I guess thats my problem there :P

Thanks in advance.

[tomcug]

Drizzt5, I think you should begin with checking your card's voltage with stock BIOS. It's impossible to reach 1,3V with just modded BIOS. What's more, the BIOS you flashed your card with has a stock 3D voltage. I think you've set your DMM to right spot, so this isn't your problem. I always use my case as a ground and it works pretty good, voltage measure is accurate.

[Drizzt5]

So I should reflash to my orignal bios then?

If i still have 1.3v's don't you think it's the DMM that I am doing wrong with.

I changed the DMM to 20 instead of 2 so It wouldn't round and I still got something pretty high. 1.29v's vgpu....

[me_martin]

wow that is pretty hot.. and that with aftermarket coolers?

Unfortunately yes

[tomcug]

Drizzt5, use the stop marked in yellow as a ground. If you'll still read 1,3V, then I'm out of ideas.

[Drizzt5]

It was a bad DMM, thx for suggestions. I went and purchased a good one.

[pablo NZ]

so if i'm reading this right, I can use silver conductive ink instead of a pencil for pencil-mod #2?

I just prefer ink over pencil as my pencil mods have a tendency to degrade :(

[Drizzt5]

Nice thanks wizard, I'm 780/1000 stable with the first pencil mod. I'm going to take the card out again and just try to squeeze up to 1.32-1.35 vgpu if I can. Right now I'm only at 1.28.

[yanahs]

Unfortunately yes

@me martin
I dont suppose I could trouble you for the resistance value of you L100 magic stuff.. so i can compare the resistance values with these alternatives

I'm thinking of some alternatives to pencil with the first mod (just for fun)

1.
http://www.permatex.com/products/automotive/specialized_maintenance_repair/auto_glass_maintenance_repair/Permatex_Quick_Grid_Rear_Window_Defogger_Repair_Ki t.htm

but as the tds says high conductivity.. i'd rather be safe and get the resitane value first.. adn compare it with your L100

2.
get a small piece of paper load it up with pencil lead, then tape it on the resistor :laugh:..

maybe i can get 1.4 with these options..
or can can somone help with the res value needed for the 1.4 bump.. or does it differ from each card?

cheers :toast:

[hayder.master]

w1zzard, i say only one think about guys who using pencil voltage mod they are professionals , and you are one of them

[awdrifter]

http://www.techpowerup.com/articles/151/images/vddc_pencil1.jpg

How low do I need to shade the resistance down to (in ohms) will I get 1.4v on this mod? Thanks.

[tomcug]

I've shaded it to 500Ohms and set 1,15V in BIOS to reach 1,4V. That's all you need.

[awdrifter]

Thanks for the reply. I will give it a try.

[Drizzt5]

I could not get more then 1.28 with that first one, I had to use the 2nd one to get my desired voltage, and be very careful how much you put on the 2nd one, a few strokes and it goes up like a bitch.

Of course, the pencil I'm using could just be crap.

[awdrifter]

I've shaded it to 500Ohms and set 1,15V in BIOS to reach 1,4V. That's all you need.

I just measured that resistor, it's 1880ohms, so I need to shade it down to 500ohms?

Edit: I shaded it down to 1730ohms, I got 1.275v under load now. I'm maxed out in CCC at 700mhz core but only 1085mhz on mem (I didn't do the vmem mod). I'm sure I could get to maybe 725-750mhz on the current voltage. Hopefully There will be a third party tool supporting it, or the RBE 1.14 release will fix the checksum correct flash.

[tomcug]

I just measured that resistor, it's 1880ohms, so I need to shade it down to 500ohms?

Edit: I shaded it down to 1730ohms, I got 1.275v under load now. I'm maxed out in CCC at 700mhz core but only 1085mhz on mem (I didn't do the vmem mod). I'm sure I could get to maybe 725-750mhz on the current voltage. Hopefully There will be a third party tool supporting it, or the RBE 1.14 release will fix the checksum correct flash.

You can use AMD GPU Clock Tool or newest ATI Tray Tools. Which pencil mod have you used? The first one or the second one?

[awdrifter]

I did the first pencil mod. I tried the newest ATI Tray Tools, it worked great. Now I'm at 725mhz core.

[tomcug]

I did the first pencil mod. I tried the newest ATI Tray Tools, it worked great. Now I'm at 725mhz core.

You sure you shaded it to 1730Ohms and reached 1,275V? Seems a bit too high for me at 1730Ohms.

[awdrifter]

Stock is 1880ohms, and I shaded it down to 1730ohms. It gives me 1.275v (measured) with Racedriver Grid loaded (CCC set to 700mhz). But after I got ATI Tray Tools, I set the voltage option to 1.158v, that gave me 1.325v (measured) with Grid loaded. I have a Asus brand 4850 btw.

[ASOrkan]

When i was erasing my pencilmod i think i erased too much and i cleaned up the black area of the solder (circuled one in the picture). Now its totally silver. Should i replace it with something or leaving it with this situation gives nothing bad to my card?

http://img257.imageshack.us/img257/55/vddcpencil1jo3.jpg

[tomcug]

ASOrkan, it won't cause any damage to your card, you can use it without any troubles.