VMod Controller

[ae804]

So I was stumbling around in the forums... looking for a Vmod for my 3870's when I had an amazing idea...

I'm taking micro controller classes at college and have been trying to find something fun to do with the information. I realized that there are digitally controlled Variable Resistors. It got me thinking... Wouldn't it be useful if you could create a device where you would solder the wires to the appropriate place on the GFX card and then using the computer you could change the resistance through Software?

It could be pretty universal. Here's what I'm thinking:

Microcontroller (Duh) with serial communication with your computer (maybe in a different version, it could communicate through USB to make this useful on more computers) and I2C communication for the "extras"
"Extras":
4 Digitally controlled VR's (Vcore and Vmem on two cards), controlled by the I2C bus
4 Analog to Digital converters to test the voltage at each necessary points (Vcore and Vmem on two cards)
Finally, just for giggles... I2C Ambient Temp monitor... I figure they're cheap and easy to implement... why not?

Oh, and a backlit LCD display to show you all the information it's collecting...

I figure as long as I make this as general as possible, there should be no reason that it can't be universally useful. You could even use it to do Motherboard Vmods.

So a few questions:
Has anyone tried digital VR's for this use before?

What values should I try to find for the resistors? -- Remember that the largest stepping I can get for D-VR's will be 256, so for a 100kOhm resistor, each step would be a 390 ohm change.
I guess I could do like a 50kOhm VR and a 50kOhm resistor, but it would limit how low you could go.


Thanks for the input,
AE

[Jimbo Mahoney]

On the face of it, it sounds awesome!

100k VRs would probably be most universal, but I would have though that making the circuit / software able to support a variety of VRs would be best, since some mods only require 1k VRs.

[Marvin_The_Martian]

This was something I was planning a long time, not that technically savy but I bought some parts to get me started.

Got an usb interface board with digital and pwm input and outputs and a pic programming board, the interface board I been using with some other projects but I never got around to even testing if the pic programmer board I put together is working properly.

Any, thread subscribed as I really wanna see if you're going to be able to pull this off, and more importantly if you can make it cheap and reproducable, something I probably wouldn't be able to since I'm using the interface kit from velleman.

[ae804]

On the face of it, it sounds awesome!

100k VRs would probably be most universal, but I would have though that making the circuit / software able to support a variety of VRs would be best, since some mods only require 1k VRs.

Hmmm I'll have to look around and see if I can find a pot that runs from 1k-100k and uses same signals/addressing/etc.

[Edit] I've found a few that run 2.5kOhm to 100kOhm.... That seems like it would work. Step would be about 10 ohm's I'm pretty sure.

[TI66ER]

Very nice idea,put me down for one when you can make em :D

subscribed to this thread,this is interesting enuff to keep an eye on.

[billdavis]

you have something here

build it and we will come

[4Qman]

Very interesting and i hope it goes to plan. :)

Although id be a little worried having a controller deciding the life of my card. I mean id be checking the voltage was always what it should be.

Good luck

[ae804]

Very nice idea,put me down for one when you can make em :D

subscribed to this thread,this is interesting enuff to keep an eye on.

Sounds Great!!! That's 2 Subscribed with just an idea.... I hope I don't dissapoint :p:


you have something here

build it and we will come

Sounds great!!! Hopefully I can make some $$$ off this


Very interesting and i hope it goes to plan. :)

Although id be a little worried having a controller deciding the life of my card. I mean id be checking the voltage was always what it should be.

Good luck

Yea, that's why there will be significant testing before I put this on even my cards. Honestly though, the pot values shouldn't change unless you tell the software to change it..... Like I said, it'll take a lot of testing to be certain enough that it's working...



So quick kinda/update:
I've created some quick Psudo-Code for what I'm thinking... Picked out parts and am getting excited :D

Right now, I'm looking for an LCD to use and a place to get PCB's made.... Anyone know any information for either (maybe someone who made a controller for Phase systems--hint hint)

I wouldn't expect this project to move too fast--I still have classes, swim practices and Graduation coming up, so I'm pretty busy. I'll try to keep this updated and will try to add pictures once I have stuff to take pictures of (I know how forum dwellers love pictures ;) )

So, until later,
AE

[n00b 0f l337]

This is sorta what Hipro has done with the Maximizer, except manual control. Even more useful to have it manual or settable that way you dont have to have the computer on to adjust.

[Ace123]

subscribed, Count me in.

[ae804]

New update-- I figure it's been a week at this point and since I have more news, I'll share it with you all!

I've been looking at parts. Today I ordered the hardware and the extra pieces to make it on a bread board. Hopefully I'll get the parts in very soon and can start playing with them. I'll look into NoL has suggested and have an easier way to change the resistance values (other than the computer). I figure I should be able to implement both.

I'm looking into making a gui for this in windows--Hyperterminal is not the best program to use (and honestly I'm not too happy using it because not all motherboards have serial connections any more).

Hopefully if I talk to the right professors, I'll be able to figure out USB communication.

So, that's all I got for now.

[Ace123]

Keep em coming man

[Power5]

How hard is it to solder to a GPU on that tiny of a scale?

I would definately be interested in something like this though. Great initiative.

[ae804]

How hard is it to solder to a GPU on that tiny of a scale?

I would definately be interested in something like this though. Great initiative.

It won't be any harder than soldering a Variable resistor to the same spots.

That's the beauty of this! It works the same as a variable pot, but can be controlled by the computer or by push buttons instead of finding a tiny screwdriver to turn the screw.


Keep em coming man

Will do!

Parts have come in (for the most part). I've misplaced a couple, but I'm sure they're in my room. Tomorrow is cleaning day, so when I have found everything, I'll post some pics!

[ae804]

So--Today's work

Shown below are my tools and the parts that have come in.

Right to left: Solder, Soldering Iron, Programmer (The white and black pieces both), Good Drink (or two), and at the bottom the chips for the project.

http://i91.photobucket.com/albums/k315/ae804/100_0708.jpg

The VR chips for this project are MSOP surface mount parts, So I had to get a MSOP to DIP adapter. Shown in the picture below are the digital resistors soldered to the adapters. Each chip has two resistors, so for the project we'll have four total VR's (one for core and one for memory for two cards). This will be easily expandable up to four chips and eight resistors, for those of you tempted to go quad crossfire or quad SLI.

http://i91.photobucket.com/albums/k315/ae804/100_0712.jpg

Finally (and I'm sorry for the terrible image) is the microcontroller (Large Dip chip) and the programmer for it. This is the same chip that I used in one of my classes, so I have a lot of the code for this project already. I just need to put it to use correctly!

http://i91.photobucket.com/albums/k315/ae804/100_0710.jpg

Anyway, Enjoy the pictures Hopefully I'll be able to get some more news soon (working parts?)

AE

[ae804]

I know it's been a while. It's been busy the last few weeks... I basically finished my Swimming Career last weekend, I have finals this weekend and I was in a car accident early last week... ironic thing is I was looking at getting a new car the day before anyway!

Anyway. Over the next two weeks, I have a lot of extra time, so hopefully I can write some code that'll interface with the I2C VR's. I'll try to keep everyone up to date!

[Power5]

Sweet, still waiting for you. Sorry about the accident, though if you are okay, at least you get a new car out of it. I have always wanted to be hit by someone so I can get a new car, never happens though. Of course I dont want to be injured though.

[wittekakker]

This is sorta what Hipro has done with the Maximizer, except manual control. Even more useful to have it manual or settable that way you dont have to have the computer on to adjust.

Indeed, pc interface looks cool but aint very handy compared to complete dedicated PSU's.

[r4st4m4n]

Hmmm I'll have to look around and see if I can find a pot that runs from 1k-100k and uses same signals/addressing/etc.

[Edit] I've found a few that run 2.5kOhm to 100kOhm.... That seems like it would work. Step would be about 10 ohm's I'm pretty sure.

Hmm maybe it is too late, but for the 8800 (G92) GT/GTS the Vgpu needs a 500Ohms VR. At this value it only slightly overvolt and you need to decrease further the resistance in order to increase the voltage.

So if you can't go lower than 2.5kOhms, it won't work for these cards. Maybe you should look into the possibility to have 2 different ranges: 1 with high resistance and one with (very) low resistance.

Anyway your idea is neat :up:

Could you tell us how much the mod would cost ?

[lachinois]

Hey that mod sounds really cool! Subscribe me in!

[ae804]

Hmm maybe it is too late, but for the 8800 (G92) GT/GTS the Vgpu needs a 500Ohms VR. At this value it only slightly overvolt and you need to decrease further the resistance in order to increase the voltage.

So if you can't go lower than 2.5kOhms, it won't work for these cards. Maybe you should look into the possibility to have 2 different ranges: 1 with high resistance and one with (very) low resistance.

Anyway your idea is neat :up:

Could you tell us how much the mod would cost ?

Sorry that it's been a while. I've been busy working on my senior project and still haven't had much time for this. It's still on my to-do list.

Anyway, The pots that I did are 100k, 50k, and 2.5k max. This means that the chips can go from 0 (ish) all the way up to that max value. Hopefully when I get this working, I'll be able to see how well the 2.5k resistor works for the G92 cards. I'm more worried about the 3870X2's which I think have a 100 (or is it 50) ohm resistor....? We'll see. Also for memory and core, I can install two different chips if necessary that will have different max resistances.


As for how much this has been so far, I have spent about $40 on parts so far and have bought 2X the parts I need. Granted, this is without a PCB or the LCD.

I'll have to get some code working here soon to show ya'all how it works.

AE