How-to: Pencil mod your HD 3870!

[Cold Storm]

Yeah, it didn't take me long to do mine. The million times I have done it. But, after time, you gotta do it again.. thats the thing that I don't like.. Trimpot thing looks great, just have to get it on here again.. lol... RM Your "new" baby is going to want a reshadding, when she gets into your hands!

 

[DanishDevil]

I was thinking that there might be a way to make it more permanent. I have no idea what the electrical conductivity of candle wax is, but if it's nothing, then a little dab of hot candle wax over the shaded resistor would just about make it permanent, no?

 

[sneekypeet]

clear nail polish!

 

[Cold Storm]

That would keep the mod in tacked? tell me more wise one!

 

[DanishDevil]

Well, the graphite sitting on top of the resistor is what's allowing more voltage to jump from one end of the resistor to the other, right? And I assume that the graphite's effects fade over time because it's knocked or blown or brushed off. Pencil lead never needs replacing because it "spoils" in pencils, so I doubt it spoils in conducting electricity, as nobody reported that new pencils work better than old ones.

So, get something like that epoxy crap that most of us had to scrape off to get good adherence to the resistor and/or PCB and cover the shaded resistor with it. I haven't tried it, but it should work in principal.

 

[DanishDevil]

clear nail polish!

Can you confirm that it's not electrically conductive? I guess I could make a puddle of it on a piece of metal, let it dry, and test its resistance. I will this weekend.

 

[sneekypeet]

its like polyurathene...make a hard non conductive permanent cover for the Vmod done in pencil.

I stress permanent tho....acetone may remove it but its not a guarantee.

just need a little drip on the end of a toothpick.

At Danish devil....woldnt a dob of it applied to anything show a reading if it was conductive.
I can put a dob on a piece of marble and test with my DMM to see if it is or not!

 

[DanishDevil]

Well you could probably just pop it off with a careful hand and a knife, no? That's what my mom used to do whenever she spilled nail polish on the counter And after a while, that stuff just chips off your fingers anyway. I doubt it'd rip the resistor off with it.

 

[Cold Storm]

yeah, but I don't know how if you get that knife to scratch that resistor.. thats my worry for it. I mean, if you got the volts you want, then hell yea on nail polish... I know I could never send mine into RMA. LOL. RM your something else!

 

[sneekypeet]

Well you could probably just pop it off with a careful hand and a knife, no? That's what my mom used to do whenever she spilled nail polish on the counter And after a while, that stuff just chips off your fingers anyway. I doubt it'd rip the resistor off with it.

Agreed on the "pop off" factor. I guess it depends on how well it gets cleaned prior to application.

 

[DanishDevil]

Well, I used a thing that I used to use when I built those little model kits of cars and airplanes, kind of like a small nail file. I used that to scrape the short way against the resistor so that the graphite would fill in the small gaps made by it when I shaded it the long way.

 

[sneekypeet]

just tested it on the block of stone...it shows absolutely no conductivity!

 

[DanishDevil]

Thanks! I think that should do for a permanent pencil mod. Anybody daring enough to do it before I get home on Friday and risk the card I thought I killed already?

 

[Cold Storm]

RM might do it to his new one?!?! well mine... He's all ready killed it, and voided warr. so why not that?!?! But, its up to him, and probably won't be till this weekend.

 

[DanishDevil]

That'd be sweet. BTW - who said you had to reapply it anyway? I'd like to ask them why you'd have to. There may be a reason other than the graphite coming off the resistor.

 

[croni-x]

yea, if there was a resistor there, it would work. i've notice a lot of the newer 38x0 cards that don't have an r1222... surely this is because they caught wind of the pencil mods?

I measured the resistor and its value is 2,66kOhm, is that okay ? I found a thread about pencil modding a HD3850 and that guy talked about a resistance of 5,5 Ohm (wtf??). In which steps should i lower the resistance and measure the VGPU not to risk my hardware?

greets
croni-x

 

[DanishDevil]

I can't give you an Ohm to Voltage comparison for your card, but a few things you need to make sure of first.

When measuring resistance, have your multimeter set to the 2k resistance, and to measure voltage, have it set to the 20 V setting. Measure resistance with the card out of the case, and measure voltage during boot.

We need to find a vGPU measure point for you. You want the red touching the vGPU measuring point, and the black touching the bare metal of your case. It's going to be one of the raised bumps to the left of your resistor (near the left border of the picture) I'm guessing. I'd have RM double check that.

RM! We need a vGPU measuring point for our non-reference 3850 owner here!

 

[Random Murderer]

RM might do it to his new one?!?! well mine... He's all ready killed it, and voided warr. so why not that?!?! But, its up to him, and probably won't be till this weekend.

sure, why the hell not?

I can't give you an Ohm to Voltage comparison for your card, but a few things you need to make sure of first.

When measuring resistance, have your multimeter set to the 2k resistance, and to measure voltage, have it set to the 20 V setting. Measure resistance with the card out of the case, and measure voltage during boot.

We need to find a vGPU measure point for you. You want the red touching the vGPU measuring point, and the black touching the bare metal of your case. It's going to be one of the raised bumps to the left of your resistor (near the left border of the picture) I'm guessing. I'd have RM double check that.

RM! We need a vGPU measuring point for our non-reference 3850 owner here!

i need a pic of the back of the card.

 

[DanishDevil]

You need more than this?

 

[Cold Storm]

Hey, its your card now! lol.. happy b-lated birthday.... Thats what I wanted to give ya for your birthday man... Dang tax returns

 

[Random Murderer]

You need more than this?

yep.

 

[MagnusLL]

I hate redoing this, but... any help for soldier points for a trimmer gpu vmod on the Powercolor 3870 (and vmem soldier and measure points, if at all possible)?

I'll relink the images originally posted by Cuboard:

 

[croni-x]

The vGPU Point are no problem i found several of them almost equal to other references, i have 1,24V on there. Okay i will measure the resistance again, but this time i will take the card out of the case. My multimeter finds the range it's self, so there is no setting for 2kOhm or 20V, but it worked fine on other resistors.

 

[freaksavior]

Maybe someone can help.

I got the vcore up to 1.45. and every 3d app crashes. any idea? btw stock frequencies

 

[DanishDevil]

Anything above 1.44V on my HIS and I get the same thing. Is it immediate or does it happen after a short period of time, like 10 seconds? Mine was the latter.

The vGPU Point are no problem i found several of them almost equal to other references, i have 1,24V on there. Okay i will measure the resistance again, but this time i will take the card out of the case. My multimeter finds the range it's self, so there is no setting for 2kOhm or 20V, but it worked fine on other resistors.

Sounds good. What I would do is make a chart like I did, and plot what voltage you get from what resistance. Just be sure to blow off the pencil dust. That stuff almost killed my card, and I wouldn't want it on my motherboard!