ATI 4850/4870 voltmod thread

It depends what the stock resistance of the circuit is. The rule of thumb is start with 10 to 15x the stock resistance.

If the circuit is 1000 ohms, use a 10 or 15k vr (I usually use the higher of the two). The VR is creating a divider in the circuit causing the total resistance to be less. As you turn the VR from its highest point to its lowest point you need more control which the lower value VR provides because it adjusts the circuit a smaller amount at a time.

Also if accuracy did not matter we'd all be using 10 mega ohm VR's lol ;)


As to the chip, heat wont do that. The expansion/contraction rates of silicone are extremely small given the temperatures it is operable at.

Quote:

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Originally Posted by STEvil

It depends what the stock resistance of the circuit is. The rule of thumb is start with 10 to 15x the stock resistance.

If the circuit is 1000 ohms, use a 10 or 15k vr (I usually use the higher of the two). The VR is creating a divider in the circuit causing the total resistance to be less. As you turn the VR from its highest point to its lowest point you need more control which the lower value VR provides because it adjusts the circuit a smaller amount at a time.

Also if accuracy did not matter we'd all be using 10 mega ohm VR's lol ;)


As to the chip, heat wont do that. The expansion/contraction rates of silicone are extremely small given the temperatures it is operable at.

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I've always heard 20x, but it doesn't need to be super accurate anyway.

I was speaking specific to this thread, and the stock reading on the PCB is ~5k, so most folks are using 100k VR's. The poster said he was using a 25k VR, and thought a 10k VR would work better...I disagree.

About my dead GT...It was my first time mounting on to a naked die. After the card popped while running FUR I took it out and dissected it. The first thing I noticed is that the PCB was bent from the excessive pressure I used while tightening the nuts. Then while loosening the nuts I noticed that the bracket wasn't all the way snapped in on 1 corner. When I wiped the core clean I noticed one corner looked chipped off slightly.

My conclusion was that the heat coupled w/ the uneven pressure caused disaster. It was probably a lot more due to the uneven pressure since temps were still in the 60's, but I have to assume the heat didn't help b/c it was fine up until that point.

Got my 4850 :)
installed my Accelero S1 rev.2, Twistytied a 120mm Delta TriBlade EFB and 70mm YSTech for the Vregs/Inductors, and am using Coolaboratory Liquid Pro.

Temperatures are 39C Load @ 675/1025 after 30mins of ATITool using 1.2v from Bios. Off to do the vmod :p

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Originally Posted by jason4207

I've always heard 20x, but it doesn't need to be super accurate anyway.

I was speaking specific to this thread, and the stock reading on the PCB is ~5k, so most folks are using 100k VR's. The poster said he was using a 25k VR, and thought a 10k VR would work better...I disagree.

About my dead GT...It was my first time mounting on to a naked die. After the card popped while running FUR I took it out and dissected it. The first thing I noticed is that the PCB was bent from the excessive pressure I used while tightening the nuts. Then while loosening the nuts I noticed that the bracket wasn't all the way snapped in on 1 corner. When I wiped the core clean I noticed one corner looked chipped off slightly.

My conclusion was that the heat coupled w/ the uneven pressure caused disaster. It was probably a lot more due to the uneven pressure since temps were still in the 60's, but I have to assume the heat didn't help b/c it was fine up until that point.

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Yes, using a 10K VR on a 5K circuit would be way too small. It would actually work but if the stock voltage was 1.2 then it may jump to 1.6+ with the 10K VR intalled. Using 20x the stock resistance you usually end up using the last 25% of the VR to control the voltage.. that can be as little as 4 turns which means every 1/4 turn can mean up to .1v adjustment when getting nearer and nearer the end of the VR.

Nothing wrong with a 20x VR when you're going to run the card 24/7 and wont touch the VR often but if you are going to play with it from time to time a 10x or 15x VR will allow finer adjutment, just wont let you get back to "stock" volts (pfft, who cares lol) all the time ;)

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Originally Posted by jason4207

I killed an 8800GT w/ that program. I don't use it anymore.

Best stability test is to play games like you normally do. I use ATI Tool and benchmarks to get a rough idea, and then use actual game play to fine tune.

And some people are just looking to be stable enough to pass benchmarks. No need to run FUR in that case.

When I run FUR I feel like I'm shortening the life of the card. Just my opinion...

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i remember when we had those problems going on with our 8800gt's a few months back. after burning out my 8800gt while running the fur benchmark which was volt modded, i never ran that fur benchmark again, i stay far away from it. haven't tried it once yet on my 4850 and i don't plan on it.

i just want the card to be stable for all games that i play and for majority of benches (only one not being fur).

finally got a 4870 now.. voltmod looks quite complicated .. anybody seen voltmod info for these cards?

I have a question for you vmodders. Now, the bios vmod was quite a step for me, personally :P, but these pencil mods seem like russian roulette to a graphics card, if you ask me at least. Can any of you make an estimate of how ''safe'' and long lasting a pencil mod is, or is that question simply not possible to give a definite answer to?

Its not a definite answer for sure. Pencil mods are way too unreliable, and can wear off over time - not to mention the possiblity of graphite flakes scattered across your card. Definitely not something you want to have next to your circuits. It is definitely russian roulette if you try to do a pencil mod without a multimeter, since one strong pencil mark could definitely decrease the resistance by too much or even bridge it. Even with a multimeter, there really is no guarantee how long that pencil is going to stick. Some people have had good luck with them, but of course YMMV. I'd stick with soldering if you can

A question then... Over time wouldn't the pencil mod simply lose it's effectiveness? As in as time---------> Resistance between the points would only increase due to loss of graphite from pencil marks? And my understanding then would be that overtime, the voltage mod would reduce itself back down to stock. As in get instability, but not an over voltage condition?

yeah thats the idea. If you do Pencil mod, you have to check the resistance values on a somewhat frequent basis because that could very well happen. I don't think it would drop back down to stock, but theres a strong likelihood that it will increase in resistance over time as pencil marks get blown around by airflow and whatnot. That would definitely cause you to lose volts

With a solder mod, that wire is going to be on the point forever - granted you do a good job at soldering those damn tiny points :up:

Well, I got my resistors and soldered them on, but something kept messing up re-setting my card. So I said better safe than sorry:shrug:. All I have now is the Memory voltmodded at with the VR set for 2.07V. The second attempt on the gpu vmod will be when I get a waterblock (wating for the d-tek).

I noticed the card squealing sometimes, though. It'll make the noise for a few seconds upon boot-up and then it'll go away. Is it anything I should be worried about?

Right now my clocks are 710/1100 max stable:).

http://img110.imageshack.us/img110/2...ore2lh9er5.jpg

I've tried this mod, got it down do 4,75-ish Ohm. Cards idle at 1,08, load at 1,18-1,19..

*runs to get his pencil*

I have read through this whole thread. And have learned a lot of good advice and info. But with everyone posting different ways to do it, it gets confusing. Also for newbies, (like me), these may be hard to follow if you haven't done this before.

I found a good, and simple guide from TechPowerUp, which i haven't seen linked to in this thread. So, you can get it HERE.

The only thing i dont understand is, why for the vGPU mod, do you connect the middle and back pin of the Trimpot, and for the vMEM you connect the middle and front pin?

Also, never having done this myself, i had no idea where to get these parts. My radioshack, or frys electonics did not have any Trimpots. And neither did the big online retailers i checked at. So i googled and i found a good place, with a wide range available HERE.

I was thinking of using a trace pen instead of a pencil, but i have to test draw on some material to see what thickness yields what resistance. No good to ruin the card by bridging the points, then having to scrape it off or something. I just don't want to play with a soldering iron and my video card as a near first attempt. besides, I'd have to buy all the crap to do it. At that point, with the MM added in I'd have been better off buying a 4870 :) Cheaper.

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Originally Posted by darkskypoet

I was thinking of using a trace pen instead of a pencil, but i have to test draw on some material to see what thickness yields what resistance. No good to ruin the card by bridging the points, then having to scrape it off or something. I just don't want to play with a soldering iron and my video card as a near first attempt. besides, I'd have to buy all the crap to do it. At that point, with the MM added in I'd have been better off buying a 4870 :) Cheaper.

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You mean like an electrical trace pen? It yields way too low resistance ;)

I was worried that might be the case... drat. Even a super thin line? I'll have to do some tests with some plastics and what not. hmm.. or perhaps some old card I have laying around so i can see if the material has an effect. I may just use the pencil... But i got really good at making thin lines with the trace pen :) better then pencil technique on thunderbirds, and thoroughbreds.

what is the highest possible vgpu when set it bios? what is the lowest?

I have read through this thread and realise it's way over my head! :)

I must buy myself a multimeter and learn how to use it, that would be a start I guess, then perhaps buy myself a nice soldering kit and start practicing.

I am wondering if some of you are trained engineers that got into moddin computer hardware or you were once regular computer enthusiasts who became trained engineers! :cool:

Lastly what is the rough increase in GPU and Memory clocks you guys have got from your volt-modding labours pls? (compared to an unmodded stock card).

Oh a question, anyone find the Voltage circuitry getting hot when they change to another cooler and OC? I was gonna do the hacksaw mod on my stock cooler for the back piece, and mount an Accelero S1 rev 2 on it...

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Originally Posted by Big.Wayne

I have read through this thread and realise it's way over my head! :)

I must buy myself a multimeter and learn how to use it, that would be a start I guess, then perhaps buy myself a nice soldering kit and start practicing.

I am wondering if some of you are trained engineers that got into moddin computer hardware or you were once regular computer enthusiasts who became trained engineers! :cool:

Lastly what is the rough increase in GPU and Memory clocks you guys have got from your volt-modding labours pls? (compared to an unmodded stock card).

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welder by day modder by night..lol, you can get as much as 50% more out of a 4850. mine runs good at 900, stock is 625. some members have been to 1000 on the RV770 and I'm sure Gomeler will be pushing 1100 soon, ( whoops maybe I wasn't supposed to say anything....:D)

dam from going to stock to 1.28v @ load 775mhz gpu the card throws out alot of heat !!
specially in the area of the mem v mod and gpu mod area. and gpu back side itself.
Accelero S1 rev.2 i really only have the air intake fans blowing in from the front of the case to cool the cards. [antec 900]
120mm .You really cant get many fans on the cards in cf mode.
does furmark really heat things up more than normal gaming ? @ 775/1150 1.29v i get like 60c load temps.
maybe i should get those fans that go with the cooler ?does the other cf card ever run @ load ? or just idle mode?
cant seem to get the secondary card to runn higher than 2/d mode in cf ,or at least gpuz doesnt show it really kicking in a full speed . but my 3md06 scores show it is.
i dont know. testing my 2nd card to see which one beacomes my main card for higher clock,, and other to become booster card in cf lower clocked.

thanks, and o/c software out there yet ?

could someone explain the pin out of the Trimpot's? There are 3 pins. I know the middle pin is for ground, but does it matter which of the 2 remaining pins i use?

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Originally Posted by wesleyclark

could someone explain the pin out of the Trimpot's? There are 3 pins. I know the middle pin is for ground, but does it matter which of the 2 remaining pins i use?

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you need to measure the resistance to determine which pin to use. I adjust it so that the desired pin has the rated resistance I am looking for then remove the other pin to avoid a mistake.

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Originally Posted by jimmyz

you need to measure the resistance to determine which pin to use. I adjust it so that the desired pin has the rated resistance I am looking for then remove the other pin to avoid a mistake.

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That makes sense. So you could use either pin, it just depends on which way you want to turn?

Quote:

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Originally Posted by wesleyclark

That makes sense. So you could use either pin, it just depends on which way you want to turn?

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yep, I make sure mine turn the same as each other.

Quote:

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Originally Posted by jimmyz

yep, I make sure mine turn the same as each other.

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Alright. Thanks for the info. That helps clear up a bit for me.

Also, could someone explain to me jason4207's use of the molex plug in his mod found HERE.
I think he is using it as a switch to enable/disable the mods, but i am unsure of how it works unless he has the female adapter with cables connecting both the vgpu and vmem to the ground.

And also, where is a good place online that you get your Trimpots from?

I like to set them so that clockwise results in the resistance lowering...which results in the voltage rising. It's just like turning up the stereo volume!

Quote:

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Originally Posted by wesleyclark

Alright. Thanks for the info. That helps clear up a bit for me.

Also, could someone explain to me jason4207's use of the molex plug in his mod found HERE.
I think he is using it as a switch to enable/disable the mods, but i am unsure of how it works unless he has the female adapter with cables connecting both the vgpu and vmem to the ground.

And also, where is a good place online that you get your Trimpots from?

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That molex is a convenient way to measure the vGPU, and vMEM. I simply stick the black probe into the GND molex hole, and the red probe into the vGPU molex hole or vMem hole to measure the respective voltage.

Like this:

http://img520.imageshack.us/img520/9...0005bz1ri4.jpg

I usually order from Mouse Electronics, but i like the Allied Electronics website better. DigiKey is another one.

Quote:

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Originally Posted by jason4207

That molex is a convenient way to measure the vGPU, and vMEM. I simply stick the black probe into the GND molex hole, and the red probe into the vGPU molex hole or vMem hole to measure the respective voltage.

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hey, that's a pretty good idea. I was only going to add a simple slider switch to disable the mods if i needed to, but now i might also add a molex, or something similar to get the voltage readout function too!

And i hope you didn't take that above pic just for me. Haha :rolleyes:

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Originally Posted by wesleyclark

hey, that's a pretty good idea. I was only going to add a simple slider switch to disable the mods if i needed to, but now i might also add a molex, or something similar to get the voltage readout function too!

And i hope you didn't take that above pic just for me. Haha :rolleyes:

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It's been stored on Imageshack for a while. ;)

You'll also notice that the blue VR's are inserted into the 3-pin fan connectors. Simply pull the VR out, and you're back to stock voltages. :up:

Quote:

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Originally Posted by jason4207

It's been stored on Imageshack for a while. ;)

You'll also notice that the blue VR's are inserted into the 3-pin fan connectors. Simply pull the VR out, and you're back to stock voltages. :up:

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haha, i guess that works too.

so, just to make sure i get this right. Im trying to make things as clear cut for me, and any one else new to this. I've made a clean schematic labeling everything that needs to be done, and all of the measurement points. Can you let me know if i am missing anything or messed up on anything.

The is the main area.
http://iwesley.org/Images/4850vmodsclip.jpg



The full image is available HERE.
The base picture i used i obtained from TechPowerUp from THIS article.

I'm in about the same position as wesleyclark, which is i'm about to mod my first card (4850)!!! And i have a few questions. First jason4207, how can you put the middle pin of the blue vr into the fan connector since it isn't in the same line with the other two, and second do i have to use these very small cables (which i don't know how they called and where to find them) you used in your mod or i could use the cables that the fan connector had?

Is the yellow spot that wesleyclark posted right? cause i have read that the right spot is this one http://img154.imageshack.us/img154/7...2lh9er5bu3.jpg
http://img154.imageshack.us/img154/7...b15803a59a.jpg
or maybe both can be used?

I would like to thank everyone for the help and the info you provide us.

I am also curious. That would make my VGPU mod much much easier..

Edit. Also, I am curious. What is the max Voltage I shoudl apply for the memory. I am at 2.07 right now at 1100mhz using the stock cooler. Thanks.

Hi, 1st post :) getting Asus 4850 in a mail tomorrow, planing to put Maze 4 on it and OC it to 800.

Quick question, what voltage do you need for 4850 GPU to reach stable 800MHz. Also is it possible to reach 800 MHz trough BIOS only or Vmod is needed.

Thanks.

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Originally Posted by eddieobscurant

Is the yellow spot that wesleyclark posted right?
or maybe both can be used?

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I think both can be used. jason4207 uses the spot that you pointed out, and jimmyz uses the spot that i pointed out. I can go add the other one to the image now.

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Originally Posted by wesleyclark

That makes sense. So you could use either pin, it just depends on which way you want to turn?

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Yes but cut it before soldering else you could start with your resistance @ 0 :D if you solder the wrong one

who has done the pencil mod? how safe is it? just a regular # 2?

is there a way to check voltage in windows? i dont have a multimeter lol

Quote:

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Originally Posted by eddieobscurant

do i have to use these very small cables (which i don't know how they called and where to find them) you used in your mod or i could use the cables that the fan connector had?.

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You could use the cables that came off of the fan connector. You generally want a small cable though, so that it wont contact any other points besides the ones you need.

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Originally Posted by zaraza

who has done the pencil mod? how safe is it? just a regular # 2?
is there a way to check voltage in windows? i dont have a multimeter lol

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I am unaware of any way to check graphic card voltages in windows. If you do not have a multimeter i would not try this mod. As you may end up damaging your card if you do not have the right resistance. But yes, just a normal #2 pencil will work.

what kind of multimeter do i need? I want to try this mod, i can borrow one from a friend. And do i check the voltage when the card is off? or on? lol. Bear with me plz

Quote:

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Originally Posted by zaraza

what kind of multimeter do i need? I want to try this mod, i can borrow one from a friend. And do i check the voltage when the card is off? or on? lol. Bear with me plz

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Just a standard multimeter that can check resistance and voltages. You can get one from your local radioshack for around $20. You can check the resistance of your pencil mod while the card is off and see if it is in the correct range. But you can only check the voltages while the card is on. When you check the voltages, make sure you check them very soon after turning it on. Otherwise you may be running them to high and risk burning out your card.

Quote:

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Originally Posted by wesleyclark

haha, i guess that works too.

so, just to make sure i get this right. Im trying to make things as clear cut for me, and any one else new to this. I've made a clean schematic labeling everything that needs to be done, and all of the measurement points. Can you let me know if i am missing anything or messed up on anything.

The is the main area.




The full image is available HERE.
The base picture i used i obtained from TechPowerUp from THIS article.

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I think you have the wrong spot. You can see the trace line on the board if you look closely. Anywhere along the trace line is perfectly fine. I actually bridged two points along the line for a stronger connection. All points along the trace are electrically the same point.

It's a good idea to take resistance measurements before, during, and after you install the mods. Then you can see if your readings are matching up w/ what everyone is posting.

http://img116.imageshack.us/img116/6137/vgpuex4.jpg

Quote:

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Originally Posted by eddieobscurant

I'm in about the same position as wesleyclark, which is i'm about to mod my first card (4850)!!! And i have a few questions. First jason4207, how can you put the middle pin of the blue vr into the fan connector since it isn't in the same line with the other two, and second do i have to use these very small cables (which i don't know how they called and where to find them) you used in your mod or i could use the cables that the fan connector had?

Is the yellow spot that wesleyclark posted right? cause i have read that the right spot is this one
or maybe both can be used?

I would like to thank everyone for the help and the info you provide us.

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All 3 pins on the VR's I have slide perfectly into a 3-pin fan connector. I'm not sure what you mean about them not lining up.

I have found that if you don't use smaller cables your mods are much more likely to pop off, and you are going to have heat the components more b/c the thicker gauge wire will wick heat away quickly. I use 30awg wire for the VR's, and 18-22awg for the read points. I hand crimp, and solder all my connections.

Quote:

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Originally Posted by adpr_02

I am also curious. That would make my VGPU mod much much easier..

Edit. Also, I am curious. What is the max Voltage I shoudl apply for the memory. I am at 2.07 right now at 1100mhz using the stock cooler. Thanks.

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I've heard anywhere from 2.1-2.2 is a safe max, but I wouldn't consider pushing it until you can get aftermarket cooling. The stock HSF puts a lot of additional heat on the RAM chips from the GPU.

Quote:

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Originally Posted by Vlad_13

Hi, 1st post :) getting Asus 4850 in a mail tomorrow, planing to put Maze 4 on it and OC it to 800.

Quick question, what voltage do you need for 4850 GPU to reach stable 800MHz. Also is it possible to reach 800 MHz trough BIOS only or Vmod is needed.

Thanks.

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Not sure exactly what voltage you'll need, but I think BIOS editing will only get you to 720-750MHz.

Quote:

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Originally Posted by zaraza

who has done the pencil mod? how safe is it? just a regular # 2?

is there a way to check voltage in windows? i dont have a multimeter lol

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You need a DMM to even consider doing this. They are a lot cheaper than a new gfx card.

OK. My original image in post #231 has been updated HERE.

The reason i used the pin i did in the first version of my image is because in one of Jimmyz's posts, he said to use the pin next to 601. HERE.

Is that not correct?

Quote:

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Originally Posted by wesleyclark

OK. My original image in post #231 has been updated HERE.

The reason i used the pin i did in the first version of my image is because in one of Jimmyz's posts, he said to use the pin next to 601. HERE.

Is that not correct?

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Those 2 points might be tied together via sub-layer traces. Check the resistance b/n the 2 points in question. It should read very low 0-0.3Ohms.

As long as you're reading ~5k from the proposed mod point to ground then you're probably in the right spot.

is there any sort of mod that we can do to increase available Power draw on the 4850???

The 4850 supports a max draw of 150W, 75w on the 6pin, and 75w on the PEG.
The 4870 supports a max draw of 225W, 150w on the double 6pins, and 75w on the PEG......

If ATI puts two connectors on @ 750MHz core + DDR5, that is telling you something right there already. We are running 900~MHz on a single connector

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Originally Posted by jason4207

I think you have the wrong spot.

http://img116.imageshack.us/img116/6137/vgpuex4.jpg

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Actually, it's where I've used as well. Easier to get to without the possibility of contacting anything.

Same as the other spots, connected by an inside trace.

So i just got back from radioshack. Only to find out that my Multimeter needs a batter which i don't have, and to find that the soldering iron i got doesn't get hot enough to melt the solder on the boards. AND to find that my solder fell out of a hole in the bag when i was walking home... this is a great day. Ill be going back later tonight and pick up some more solder and get a different iron.
What wattage would you recommend for a soldering iron for this kind of work? I bought a 15 watt, and it isn't powerful enough.

Quote:

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Originally Posted by wesleyclark

So i just got back from radioshack. Only to find out that my Multimeter needs a batter which i don't have, and to find that the soldering iron i got doesn't get hot enough to melt the solder on the boards. AND to find that my solder fell out of a hole in the bag when i was walking home... this is a great day. Ill be going back later tonight and pick up some more solder and get a different iron.
What wattage would you recommend for a soldering iron for this kind of work? I bought a 15 watt, and it isn't powerful enough.

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15W is plenty if you know what you're doing.

If you're referring to melting the main solder posts on the card, you simply need to re-tin the area with fresh solder, and then it will work out perfectly.

For all the SMT and small spots on the board, 15W is more than enough...

For anyone interested, I've played around for the last day or so with a lot of different levels of resistance. I had asked a little while back if anyone had any fixed resistor values, and nobody did.

If anyone is interested in fixed values (assuming 1.046v IDLE / 1.084v LOAD in BIOS), here you go:

vMEM: 100k (5%) Fixed Resistor = 2.1v ~ 2.12v

vGPU Idle: 27k (5%) Fixed Resistor = 1.17v ~ 1.20v

vGPU Load: 27k (5%) Fixed Resistor = 1.30v ~ 1.33v

I played around with VRs, but just wanted something solid for this round of testing. Hope this helps somebody out there...

@wesleyclark: Yeah I got a smallish DMM and it needed a sort of strange 12v battery... I think I may even have a soldering iron around here. Probably better that you don't have a huge amount of power for that soldering iron, less easy to melt something horribly necessary. (Like the original solder points).

Quote:

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Originally Posted by darkskypoet

@wesleyclark: Yeah I got a smallish DMM and it needed a sort of strange 12v battery... I think I may even have a soldering iron around here. Probably better that you don't have a huge amount of power for that soldering iron, less easy to melt something horribly necessary. (Like the original solder points).

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yeah, i found pretty much the cheapest DMM i could find at radioshack. Its a shame they wont just put a AA on it or something and be nice to us. As for the iron, the reason i got the 15, was so that i wouldn't melt things. I didn't think to try using a little new solder to melt the old. Ill try that once i replace my lost solder tonight.

Quote:

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Originally Posted by Theta

For anyone interested, I've played around for the last day or so with a lot of different levels of resistance. I had asked a little while back if anyone had any fixed resistor values, and nobody did.

If anyone is interested in fixed values (assuming 1.046v IDLE / 1.084v LOAD in BIOS), here you go:

vMEM: 100k (5%) Fixed Resistor = 2.1v ~ 2.12v

vGPU Idle: 27k (5%) Fixed Resistor = 1.17v ~ 1.20v

vGPU Load: 27k (5%) Fixed Resistor = 1.30v ~ 1.33v

I played around with VRs, but just wanted something solid for this round of testing. Hope this helps somebody out there...

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That's simple to know what resistance you need to get the voltage you want.

For example : Vmem
-Stock resistance before chip is 3.94k. Stock voltage is 2.04v.
If you put a 100k resistance in // with the stock resistance, you get :
Req = 1/(1/3940+1/100000) = 3.79k
Then Vnew = Vold * Rold/Rnew = 2.04*3.94/3.79 = 2.12v

If you want to find the resistance (Rnew) you need to set in // in order to get your new voltage (Vnew) assuming stock voltage (Vst) and stock resistance (Rst), just use this formula : 1/Rnew = Vnew/(Vst*Rst) - 1/Rst

R in ohms and V in volts :D

I May have the V-mod for a 4870 to test, someone who owns a 4870 and a MM please PM me.

This means someone who knows that it will void their warranty and is willing to try out the mod, I don't have a 4870 or I would test it myself.

I've got a problem. I soldered my 100k ohm resistors in the rigth place, and can overclock more, so obviously it works. However, when I try to change them so I get more voltage, no matter which dirrection I go, or how much I turn, the voltage does not change..... Anything I'm doing wrong?

Shut down the PC, turn the VR and check the resitance between the 2 pad you could do a pencilmod with, it will give the reistance you have now before the chip : does it change?

It doesn't change.... Wth... It changed when I moved them before I hooked them up..

Maybe I got the wrong thing... They're yellow, not blue. I'll post an image in a sec.

Pic. They say 64W 100k-k 9232...
http://img.photobucket.com/albums/v4...2/IMG_3596.jpg

The mess gets cleaned up after I figure it all out. BUt this is weird. and I've scrued with the VRs so much that I hav no idea what resistance they're at. But still, my card is getting the proper voltage for my current overclock.

wesley ;)

like this ?

http://img185.imageshack.us/img185/8...odsclipgb2.jpg

@fatalbert, that is exactly correct. Just make sure you turn the Trimpots to maximum resistance before you power up. Measure them with a Digital Multimeter. Depending on which way you want to turn the dial on the Trimpot, you could connect the outside wire on the other side.

it's not for me ;)

thanks for the advice :D

Damn.. testing atm - my card wont even do 825 @ 1,45v... :hm:

Fixed. Didn't realize how many turns it took to actually get the damned things to go down in resistance :p:

Ok - checked the vGPU. Somethings is wrong, it shows 1,2v :(

That happens when you use VR's that are too high resistance (adpr_02).

Wheelman - what VR did you use?

BIOS-mod - 1,45v (+ a small pencilmod, 4,77ohm)

Did you really measure 1.45v with a DM?

Here's a really simple excel tool to know the resulting Voltage and/or the needed resistance : Link. When enterred values aren't correct, the corresponding cases are blank.

Quote:

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Originally Posted by wesleyclark

yeah, i found pretty much the cheapest DMM i could find at radioshack. Its a shame they wont just put a AA on it or something and be nice to us. As for the iron, the reason i got the 15, was so that i wouldn't melt things. I didn't think to try using a little new solder to melt the old. Ill try that once i replace my lost solder tonight.

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Its not that you are trying to melt the old... Its that you don't need to. (at least I think...) You would just need to solder the new wire, etc down to that point by melting the new solder, I think you would lay down the new solder first then the wire and more solder.. its so you have 'glue' on either side so to speak. At least I think this is how... (please someone correct me if I am wrong)

I would anticipate on something like that card, the solder they would use would have a higher melting point then the little stuff you'll use to tack your wire down to it with. Mainly because its done in a large industrial setting, and ofttimes has to bind components onto the pcb... Further, it'll be designed to take a huge thermal load over and over and over again... So I doubt they'd have used something like what you will be for the little mod.

So correct me if I am wrong... but you aren't meant to, and don't need to melt the existing solder points. Instead your soldering something onto it... and as such, only need to melt your solder so it 'sticks' to the existing point and holds your wire in place with good electrical conductivity.

Quote:

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Originally Posted by Clemmaster

Did you really measure 1.45v with a DM?

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No, i set 1,45v in the BIOS-mod program.

Gave it up - pencilmodding atm, 60*C max at 1,35v stock speed, 3,88Ohm (just testing max voltage).
2,8ohm wouldn't boot, lol.

I'd recommend anyone who is planning on soldering to read through this guide first. :up:

Got the cards up to 1,63v load - just flashed to 1000/1100 :D

Results tomorrow ;)

Quote:

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Originally Posted by darkskypoet

Its not that you are trying to melt the old... Its that you don't need to. (at least I think...) You would just need to solder the new wire, etc down to that point by melting the new solder, I think you would lay down the new solder first then the wire and more solder.. its so you have 'glue' on either side so to speak. At least I think this is how... (please someone correct me if I am wrong)

I would anticipate on something like that card, the solder they would use would have a higher melting point then the little stuff you'll use to tack your wire down to it with. Mainly because its done in a large industrial setting, and ofttimes has to bind components onto the pcb... Further, it'll be designed to take a huge thermal load over and over and over again... So I doubt they'd have used something like what you will be for the little mod.

So correct me if I am wrong... but you aren't meant to, and don't need to melt the existing solder points. Instead your soldering something onto it... and as such, only need to melt your solder so it 'sticks' to the existing point and holds your wire in place with good electrical conductivity.

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"Cold joints" suck.

You should preferrably melt both the old and new otherwise the joint will be exceedingly weak and may cause resistance or no connection.

Quote:

---

Originally Posted by darkskypoet

Its not that you are trying to melt the old... Its that you don't need to. (at least I think...) You would just need to solder the new wire, etc down to that point by melting the new solder, I think you would lay down the new solder first then the wire and more solder.. its so you have 'glue' on either side so to speak. At least I think this is how... (please someone correct me if I am wrong)

I would anticipate on something like that card, the solder they would use would have a higher melting point then the little stuff you'll use to tack your wire down to it with. Mainly because its done in a large industrial setting, and ofttimes has to bind components onto the pcb... Further, it'll be designed to take a huge thermal load over and over and over again... So I doubt they'd have used something like what you will be for the little mod.

So correct me if I am wrong... but you aren't meant to, and don't need to melt the existing solder points. Instead your soldering something onto it... and as such, only need to melt your solder so it 'sticks' to the existing point and holds your wire in place with good electrical conductivity.

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You definitely want to melt the existing solder. Sometimes melting new solder can help the old melt, but what you're describing won't hold.

The traces around the smaller mod points on the board melt easily w/ a 15W iron, but the read points which have a much larger amount of metal around them are harder to heat up. The extra metal wicks up the heat from the iron, and makes it difficult to melt the solder.

You may be right about the solder having a higher melting point on the board, though, b/c it is lead-free. Nevertheless you want the all the solder w/n the joint to melt and run free. You can usually see it 'drop' when it has become 1.

I've started using 2 irons. I use my trusty 15W w/ custom sharpened tip for the finer work, and an adjustable 50W iron for the stuff that doesn't melt quickly w/ the 15W iron.

See really needed to be corrected :) and it makes sense to want to melt the two together... But for some of it... 15w might take a while. I get what you mean about the weakness of a cold joint, makes sense. I better check out that guide :)... although I think i'll pencil mod for now.

if any of you guys have GRID, can you test your overclock with it? I tried ATI tool stress test, and it was fine, i am retrying crysis to see if it loads the card more, but no matter what i do when i get into GRID the game shuts off my video card! I did flash to get 750 mhz but shouldnt it be stable at 1.2v????? unless im not getting 1.2 from the bios flash. I tried 725mhz in GRID and it too failed. The only thing i have overclocked is the core and its cooled by an S1, the ram dont have heatsinks on them yet but will very soon. Before i flashed, it would do it at 700mhz too, so im going to test it out at 700 see if it crashes. This sucks ass!

What kind of increase did you guy's see when going from 2.0 to 2.1v on the memory chips ? In the past the clocks went down when increasing the voltage. Because the boards where already running the chips to the max. Lowering the voltage sometimes gave a increase.

I'm thinking about v-modding my HD4850. But i'm also thinking of buying a HD4870. Those things have 1.26v on the core stock. And run like 790 MHz (max CCC) without a problem. I dont see my HD4850 with running 800 MHz with just 1.26v.

Well im sure it can. Gurusan did it.

@wesleyclark: Just one question for vmem. Middle pin is ground?

Quote:

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Originally Posted by Astennu

What kind of increase did you guy's see when going from 2.0 to 2.1v on the memory chips ? In the past the clocks went down when increasing the voltage. Because the boards where already running the chips to the max. Lowering the voltage sometimes gave a increase.

I'm thinking about v-modding my HD4850. But i'm also thinking of buying a HD4870. Those things have 1.26v on the core stock. And run like 790 MHz (max CCC) without a problem. I dont see my HD4850 with running 800 MHz with just 1.26v.

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Nothing for me :(

@Quake6: yes, the you can solder it to another ground if you want, this one is directly on the chip but it's not mandatory

Quote:

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Originally Posted by WheelMan

Damn.. testing atm - my card wont even do 825 @ 1,45v... :hm:

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1.417V in 3D
870Mhz stable in Crossfire :up:

Here are the values of the metal can caps if anyone is interested in seeing if adding/replacing caps will make a difference

Top Right Area of the 4850 starting from Left Side:

4x 820uF 2.5v
1x 470uF 25v Sanyo
3x 47uF 16v
1x 100uF 16v Sanyo

Bottom Right Area Starting from Left Side
1x Sanyo 100uF 16v
2x 820uF 2.5v
3x 47uF 16v

I am assuming that I am reading these ratings correctly. The Polymer Solid Cans have markings that go like this: These two are the most common:

ULR (manufacturer?)
16v (voltage)
470 (this should be 47 * 10^0 uF)
XI ( type?)

833 (type, or maybe week/batch code?)
821 (likewise this has to be 82 * 10^1 , because 821uF is not a common rating)
2.5v (voltage)

The main power filtering cap is the Black Sanyo I am guessing since its the largest? 25v 470uF

Quote:

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Originally Posted by WheelMan

Damn.. testing atm - my card wont even do 825 @ 1,45v... :hm:

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Does the screen go black after a short while?

Just got 15433 marks in 3dmark06 in vista 800/1100. Time to push higher:D

Read my posts further down.

Wouldnt do 1GHz 1,63v, trying to get 900-950 stable ;)

Quote:

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Originally Posted by zaraza

if any of you guys have GRID, can you test your overclock with it? I tried ATI tool stress test, and it was fine, i am retrying crysis to see if it loads the card more, but no matter what i do when i get into GRID the game shuts off my video card! I did flash to get 750 mhz but shouldnt it be stable at 1.2v????? unless im not getting 1.2 from the bios flash. I tried 725mhz in GRID and it too failed. The only thing i have overclocked is the core and its cooled by an S1, the ram dont have heatsinks on them yet but will very soon. Before i flashed, it would do it at 700mhz too, so im going to test it out at 700 see if it crashes. This sucks ass!

---

grid works flawlessly at 910 mhz core on mine.. haven't tried lower.. man that game looks amazing at 1920x1200 4xaa i so badly need to find an IDE drive in storage.. so i can actually get some real bench scores im getting passed up by peeps with 700 mhz core.. :down:

So it is my core not getting enough power. Damn! ill keep it stock till later today i should be getting heatsinks and a multimeter. After that i have 27 days left to return it to bestbuy if it breaks lol. I dont like how hot it runs on stock cooling.

if your using the fan header from the card then i hope you have come across this. :up:
http://www.xtremesystems.org/forums/...d.php?t=192932

Quote:

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Originally Posted by Astennu

What kind of increase did you guy's see when going from 2.0 to 2.1v on the memory chips ? In the past the clocks went down when increasing the voltage. Because the boards where already running the chips to the max. Lowering the voltage sometimes gave a increase.

I'm thinking about v-modding my HD4850. But i'm also thinking of buying a HD4870. Those things have 1.26v on the core stock. And run like 790 MHz (max CCC) without a problem. I dont see my HD4850 with running 800 MHz with just 1.26v.

---

See my quote from earlier in this thread:

Quote:

---

Originally Posted by jason4207

You are correct about the Samsung chips. My GTS w/ Samsung loves voltage. It was theorized that it wasn't the Qimonda chips themselves, but the memory controller that was causing issues on the cards that had Qimonda memory. The reasoning being that turning down the voltage actually helped one obtain higher clocks, and at the brink of stability the timings on the Qimonda chips could still be tightened w/o having any adverse effect on stability. It seemed as though something else must be at fault. The memory controller was spec'd at 1.8v, but going from 1.2ns to 1.0ns Qimonda RAM only involved pumping up the voltage from 1.8v to 2.0v on the RAM (the controller had to come along for the ride since they shared the same rail). The Qimonda RAM did fine w/ the extra voltage, but the controller wasn't stable anymore. Iirc the spec sheet on the Qimonda has them rated up to 2.5v!

Hopefully, the Qimonda RAM on the 4850 will respond well to extra voltage.

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I didn't get to do any extensive testing b/c the card I did was for someone else, but I can tell you that at stock voltage w/ stock fan speed 1200 didn't pass the CCC test, and w/ 2.09v, and the fan at 100% 1200 did pass the CCC test.


If the 4870 can easily do 790 w/ 1.26v, then why wouldn't the 4850 (uses the same core as 4870) be able to do ~800 at 1.26v? I know the 4870 has a better power delivery system, but they should still be close until you get up much further than that.

will this multimeter do the job?

http://shop4.frys.com/product/542743...H:MAIN_RSLT_PG

my 4850 is doing only 850@ 1,45V

its a bad core i think

on stock only 670 oO

my ram does 1175 @ stock

but for extreme oc on ram i need water on it

i have tested 1300Mhz @ 2,4V on passiv heatsinks and i think its to hot i get extreme artifacts

http://www.abload.de/thumb/dsc02405desktopauflsyyw.jpg

http://www.abload.de/thumb/wak3foz.jpg

greetz from germany

Quote:

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Originally Posted by zaraza

will this multimeter do the job?

http://shop4.frys.com/product/542743...H:MAIN_RSLT_PG

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That multimeter looks like will work good. And it takes a 9v battery, or 1.5v, which is good, as opposed to my stupid MM needing a 12v battery. yay

Quote:

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Originally Posted by jimmyz

I May have the V-mod for a 4870 to test, someone who owns a 4870 and a MM please PM me.

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jimmyz, could you post the proposed mod, even though though it isn't confirmed so others can look at it?

Quote:

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Originally Posted by wesleyclark

jimmyz, could you post the proposed mod, even though though it isn't confirmed so others can look at it?

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nope. Im not being a jerk I just don't want someone frying a card and saying they saw my mod and tried it. as soon as someone confirms it ( I have at least one tester) It will join the other mods in the first post if K404 wishes.:up:

@wesleyclark: Just so you know... the 12v batt I got, which yours should take as well, will resemble :

Duracell 21/23 - 12V MB21/A23 From their Security line... (as in like Car alarm Key FOBS)...

I am not sure if any of the model numbers given are Duracell specific. Got it in Walmart.. Was just on their battery shelf can't be rare at all. But there is probably a few less components required if it runs off 12v rather then 9v or 1.5v (AA) - At least I'd guess that, because our DMMs are of the dirt cheap variety :) (at least mine was, and yours is probably similar) Nexxtech I am guessing?

I got my HR03 GT today, and did the pencil mod on my 4850. Currently stable @ 800mhz 1.31v, 1130 on the ram unmodded. Hoping to get 900mhz stable. I love this card. :D

My DMM is radioshack branded. I went to 2 radioshack stored to find the battery, as it said it was available there, and NEITHER had the battery. So i am going to radioshack to return it in about 10 minutes. It was $20. Then i will be off to FRYS electronics to get theirs, which is half the price, @ $10, and uses a 9 volt or a 1.5v. So. Im happy.

Quote:

---

Originally Posted by jimmyz

nope. Im not being a jerk I just don't want someone frying a card and saying they saw my mod and tried it. as soon as someone confirms it ( I have at least one tester) It will join the other mods in the first post if K404 wishes.:up:

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That makes sense. Ill wait :)


Alright, went to Frys. Got 2x5k, 2x10k, 2x20k, and 2x100k Trimpots. If i needed a 1k for something, i could replace the 1k with a 5k correct? I would just need to turn it down a lot more before it would get effective right?
I also replaced my solder. So ill be doing a little bit of work tonight. But no DMM. The cheap ones looked pretty unattractive, so i will go back tomorrow with more money and get a nice one for about $45. That should work good. Also got some shrink wrap, and electrical tape. looks like I'm good to go.

Quote:

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Originally Posted by wesleyclark

My DMM is radioshack branded. I went to 2 radioshack stored to find the battery, as it said it was available there, and NEITHER had the battery. So i am going to radioshack to return it in about 10 minutes. It was $20. Then i will be off to FRYS electronics to get theirs, which is half the price, @ $10, and uses a 9 volt or a 1.5v. So. Im happy.

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nexxtech is the radio shack brand... Strange they didn't have the batt when walmart did... We don't have fry's up here... So couldn't take advantage of that... this one was like 20$ too. Well hey Good to hear!

Guys,

4870 diffrent PCB where GPU measure point, memory measure poit. and vmod point?

http://img57.imageshack.us/img57/7051/4870nw8.jpg

Quote:

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Originally Posted by 865pe

Guys,

4870 diffrent PCB where GPU measure point, memory measure poit. and vmod point?

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As per W1zzard and jimmyz, here is the 4870 measuring info:

Quote:

---

Originally Posted by W1zzard

http://img.techpowerup.org/080629/Capture389785.jpg

on your dmm put the black probe to ground (like case metal or the metal piece on the graphics card) and the red one to what you want to measure

yellow area and green area should be either mvddc and mvddq memory voltage (dont know which is one because i have no board). any of the pads in one color will work fine, it is safe to short between same colored pads

the blue area is vddc (gpu core voltage). as you can see two solder pads go together (white boxes on the pcb), one is ground, the other one will be vddc. test both, the one with the 0 volt reading is the gnd one. dont create shorts between those pads.

if you have questions ask before causing more damage

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im thinking we need a shot of the front for the vmod... :up:

Quote:

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Originally Posted by JamesBong420

im thinking we need a shot of the front for the vmod... :up:

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Nope... The back is easier at this point. ;)

Quote:

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Originally Posted by Theta

Nope... The back is easier at this point. ;)

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what?
enlighten me then please.....