How-to: Pencil mod your HD 3870!

[erocker]

I have deleted posts that throw this thread further off topic. Let's get back to what this thread is supposed to be about. Thank you!

 

[Random Murderer]

you need to verify the position of a resister on the PCB....looking for the thread now.

EDIT: http://forums.techpowerup.com/showthread.php?t=53220

like sneeky said, certain cards allow and certain cords don't, even if they all use the reference pcb. the only way to know is to check that resistor and if it's in the right position, try the bios mod. even though my card is supposedly able to change voltage through bios, i couldn't get a voltage boost that way, hence this thread.

 

[Dr. Spankenstein]

You could try different shading techniques. I found that if you ran your pencil over a piece of paper (while holding the pencil at the same angle) you create a "chisel-point" on the tip. Wear the pencil down until the tip is the same width of the resistor, then give one smooth, firm pass. This keeps down the "back-and-forth" motion that can actually remove some of the graphite you laid on previous passes.

Then again, some shade across the width of the resistor. It's a lot of strokes, but if you wrap your shading around to the sides of the resistor some say this method helps them reduce resistance more.

 

[Dr. Spankenstein]

Right on! Go, GO, GO!

 

[Dr. Spankenstein]

You saying you've reduced the resistance to 800ohms and you still only report 1.45V on the DMM?
That is odd...unless PowerPlay is kicking in.

Have you put a load on it (like ATITool artifact finder or RTHDRBL) to see if it changes?

 

[Dr. Spankenstein]

I was just thinking that the voltages might not kick in until the 3D clocks are activiated (gaming, benching.)

I agree, sounds like you are on the right track! Could you clarifiy your voltage under load?

 

[Dr. Spankenstein]

I think the goal would be 1.55~1.6V or aprox. 1.0k resistance. That should get you around 1GHz core.

Think the only way to get there would be the "New" or "German" mod or hard mod.

 

[kenkickr]

OK, I have tried and tried on my Sapphire 3870 single slot for a couple hours and feel I'm getting no where. My stock resistance is 1.86. the lowest I've made it was 1.79 but it seems if I blow on it or start touching it with the 4B it goes right backup. Any recommendations? Also it looks like the new mod will not work on the Sapphire single slots.

 

[Dr. Spankenstein]

@monohouse,

I guess you could combine both mods, but then I'm not sure where you would measure resistance. Were it me, I'd just do the "new" mod. As far as the 1270 resistor, I'm not sure if it is in line with the feedback pin of the voltage IC to make any difference.

@kenkickr,

That is the "rub" (sorry for the pun) with the pencil mods. Not very permanent unless you get you voltages where you want and then protect it with clear nail polish or tape. Even then, they still degrade over time. I'm sure with either a softer pencil OR a few more attempts with different shading techniques (as described a few posts back) you can reduce the resistance further. How much, I'm not sure. Just check voltages during boot and shut down if they are excessive.

 

[Dr. Spankenstein]

Did you "scratch" the PCB between those pads so the graphite will stick?

Sounds like you're getting there. Did you decide to "combo" your mods?

Awaiting new voltage readings...

 

[Deleted member 24505]

Could you possibly combine some pencil lead dust with some pva glue or something similar to make a sort of resistance paste that will not wear off? Its just an idea.If you make it well enough it could even have a certain resistance for a certain length of line of it,ie the line length of the resistor.

You can flame me if you like guys its just a wacky idea.

 

[Dr. Spankenstein]

There was a forum member (trog100) who used this mod. the first time he tried it, he had to shut down because of the rediculous voltage that was being put to the card (around 1.7V).

Starting to wonder if the layouts of the new cards have more aggressive OVP/OCP that the reference models...

 

[Dr. Spankenstein]

Whoa boy! Have fun with that one! The bonus of these is that the increased Vcore adds a little voltage to the RAM as well (watch the heat on those, RAM artifacts are pretty obvious)!

Great job on a successful mod!

Now on to posting some benchmark scores!

 

[Dr. Spankenstein]

Well, if 1GHz was your goal, you could try to remove a tiny bit of graphite (like with the point of your DMM probe) to make your volts come to 1.60V. That would take a little heat off.

Do you have a full-coverage block? That will dump a lot of heat into your loop.

 

[Deleted member 24505]

http://www.overclockers.co.uk/showp...35&name=EK HD 3870 Full Cover VGA Water Block

 

[Dr. Spankenstein]

Full coverage meaning the waterblock is cooling both the core and memory chips.

Awesome clocks though. Maybe you just use them to game and benchmark. That Bigwater isn't going to be able to keep up with your heat.

 

[Dr. Spankenstein]

Very respectable clocks, my man!

 

[KurosakiIchigo]

Hi everyone!
i broke my R1222 resistor and the card doesn't boot... if i use the trimmer mod , maybe i can repair my board ?

 

[Random Murderer]

Hi everyone!
i broke my R1222 resistor and the card doesn't boot... if i use the trimmer mod , maybe i can repair my board ?

hmm. maybe... i think the hard mod actually completely bypasses the resistor, so give it a shot.

 

[KurosakiIchigo]

hmm. maybe... i think the hard mod actually completely bypasses the resistor, so give it a shot.

thanks for the answers!!
can i have a detailed screenshot of the hard mod ?
i didn't find it!

 

[KurosakiIchigo]

thanks for the answers!!
can i have a detailed screenshot of the hard mod ?
i didn't find it!

is this pot good for the hard mod ?
http://www.webtronic.it/pages/ITA/prodotto.asp?ProdottoID=17610&FamigliaID=0

 

[Deleted member 24505]

That should be fine.

This is my 3850 mod,its the same for 3870 i believe.

 

[Random Murderer]

That should be fine.

This is my 3850 mod,its the same for 3870 i believe.

yes, it's the same for a 3870.

 

[KurosakiIchigo]

That should be fine.

This is my 3850 mod,its the same for 3870 i believe.

thanks!!!
i'll try tomorrow

 

[thoughtdisorder]

thanks!!!
i'll try tomorrow

Excellent! Take your time, be very methodical, and if you get stuck, STOP and post a question or two. We'll be here for you man! (And if Random is sleeping I'll wake his ass up!) -He's my son....