1. Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

How-to: Pencil mod your HD 3870!

Discussion in 'AMD / ATI' started by Random Murderer, Jan 2, 2008.

  1. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
    A few people have asked me how to perform this mod, and I'm kind of sick of finding the same things over and over, so I thought "What the hell? I'll write a tutorial!"

    First things first:
    I AM IN NO WAY RESPONSIBLE FOR ANY DAMAGE CAUSED BY READING THIS GUIDE, PERFORMING ANY ACTIONS MENTIONED WITHIN, OR FOR GENERAL STUPIDITY. NEITHER IS TECHPOWERUP.COM. YOU PERFORM ALL MODS AT YOUR OWN RISK.

    Things you'll need:
    1) A BRAIN AND THE ABILITY TO FOLLOW INSTRUCTIONS.
    2) A digital multimeter(DMM) that can measure VDC and resistance.
    3) A pencil, preferably 4H, but 4B works, and others have reported 2B working.
    4) Adequate cooling for the voltage you choose.
    5) A SOFT eraser. I used a "White Pearl" eraser.
    6) A can of compressed air.
    7) Either a printer or another computer, so you can view this while you're modding your card ;)
    8) Time and Patience.
    9) A steady hand.
    10) A set of... well, you get the idea ;)

    REFERENCE PICTURES:
    [​IMG]
    [​IMG]

    Your default values may, and probably will, vary.
    Second picture courtesy of FreakSavior.

    Procedure:
    Measure the 3D voltage of your card, make sure you are running a 3D intensive application, like the 3D window in ATiTool or the Fur Benchmark.
    Do this by taking the negative lead of your DMM and grounding it to your computer chassis, and taking the positive lead of your DMM and touching it to one of the four measure points in the picture until the value displayed on your DMM stabilizes. Write this value down.
    Shut down your system and remove your card. Test the resistance of R1222. The value should be around 1.5 KΩ. Write your value down. Grab your pencil and LIGHTLY shade resistor R1222. You may need to rough up the resistor slightly with a fine file. Blow off the excess pencil lead now and then and measure the resistance, for now we're shooting for .5 KΩ less than your default. Keep repeating the shading process until you reach this point.
    Once you reach this point, the moment of truth arrives. Re-install your card, boot your system, and be sure to watch your temperatures as soon as Windows is booted. Run the fuzzy cube in ATiTool and re-test your VCore with the method from earlier and begin your overclocking!
    If you don't have enough voltage, or you think you can push it further, you can always remove your card and continue shading to drop the resistance even more, just keep in mind that the temperature scaling is in no way linear to the amount of voltage, it is more exponential.

    My Results:
    Resistance stock: 1.5 KΩ
    Voltage stock: 1.35 V under load
    Core speed stock: 775 MHz
    Resistance after mod: .933 KΩ
    Voltage after mod: 1.44 V under load
    Clock speed after mod: 891 MHz

    Removal / Reversal of the Mod:
    Just erase it! Make sure to erase lightly so as not to damage the resistor and test the resistance after erasing.

    Things to Keep in Mind:
    You'll need the fixed bios to reach speeds above 864MHz, so if you keep locking up here, it's not a lack of voltage.
    This mod is easily reversed, and undetectable(once removed) if done correctly.
    The temperature scaling is in no way linear to the amount of voltage.

    BIOS Mods:
    WARNING: Do not attempt to flash your card unless you know EXACTLY what you are doing.
    I have put together and uploaded a .ZIP that contains ATIWinFlash 2.0.0.2, the PLL fix bios(named RV670 XT.BIN), and two overclocked BIOS files, one that runs 875/1250 and one that runs 860/1200, both named after their speeds(one is 8751250.sb, the other is 8601200.sb). Thanks to IAX-Tech for the modified BIOS files.
    NOTE: These BIOS files DO NOT modify the voltages, just clock speeds, so it is still necessary to perform the volt mod.
    I have also included a new .ZIP file that has a 38xx BIOS editing program. This does not work for the X2, so users of that beast should look elsewhere(sorry guys!).

    This guide is a constant work-in-progress; if you have any questions or suggestions, don't hesitate to post them here or PM me.
    Thanks to the guys over on XtremeSystems for putting their cards on the line to figure all this out.


    BIOS editor

    Attached Files:

    Last edited: May 8, 2008
    tbar, _JP_, angelkiller and 29 others say thanks.
  2. a111087

    a111087

    Joined:
    Apr 2, 2007
    Messages:
    2,741 (1.02/day)
    Thanks Received:
    193
    Location:
    US
    1st!
    lol, nice tutorial, good pic and seems like this card will go very far with good cooling
    EDIT: sticky?
  3. cdawall where the hell are my stars

    Joined:
    Jul 23, 2006
    Messages:
    20,668 (7.01/day)
    Thanks Received:
    2,980
    Location:
    some AF base
    great guide rm
  4. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
    Yep. One guy over on XS reached 1200 MHz using LN2.

    Thanks.
  5. ShadowFold

    ShadowFold New Member

    Joined:
    Dec 23, 2007
    Messages:
    16,919 (6.95/day)
    Thanks Received:
    1,644
    Location:
    Omaha, NE
    Will this work with a HD 3850?
  6. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
    Yep. Same resistor, different VCore measure point. I just don't have a 3850 on hand to make pictures of that though.
  7. reverze

    Joined:
    Dec 28, 2007
    Messages:
    1,368 (0.56/day)
    Thanks Received:
    131
    Thanks, can't wait to give it a go! :toast::cool:
  8. ShadowFold

    ShadowFold New Member

    Joined:
    Dec 23, 2007
    Messages:
    16,919 (6.95/day)
    Thanks Received:
    1,644
    Location:
    Omaha, NE
    So what does this do? Just make it faster? It wont destroy it right?
  9. Lazzer408

    Lazzer408

    Joined:
    Jan 6, 2007
    Messages:
    2,534 (0.91/day)
    Thanks Received:
    329
    Location:
    Illinois
    How is it you guys figure out these mods? You have a source for schematics or something?
  10. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
    It depends on how much you lower the resistance and how well you cool the core.
    ShadowFold says thanks.
  11. ShadowFold

    ShadowFold New Member

    Joined:
    Dec 23, 2007
    Messages:
    16,919 (6.95/day)
    Thanks Received:
    1,644
    Location:
    Omaha, NE
    I have the HIS IceQ i think I can adequatly cool it :rockout:
  12. membreya New Member

    Joined:
    Oct 6, 2007
    Messages:
    16 (0.01/day)
    Thanks Received:
    0
    lower resistances, increase voltage..nah can't see it killing your card if you don't know what you're doing.

    :rolleyes:
  13. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
    You can always try it, just watch your temperatures closely!
  14. xt198 New Member

    Joined:
    Dec 18, 2007
    Messages:
    27 (0.01/day)
    Thanks Received:
    1
    Location:
    Hungary
    holysh.... 891 core clock. i dont have ati, and i wont buy ati cards, but i see they are very capable to overclock :p
    My question is:
    if i overclock it from software (ex: to 800mhz core clock) and i make this pen-modding too, it will give more core clock, or the software is just activating in windows?
  15. tigger

    tigger I'm the only one

    Joined:
    Mar 20, 2006
    Messages:
    10,183 (3.31/day)
    Thanks Received:
    1,399
    That should be fine.
  16. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
  17. trog100 New Member

    Joined:
    Dec 18, 2005
    Messages:
    4,420 (1.40/day)
    Thanks Received:
    237
    nice one random.. there is always a risk with this sort of stuff.. the bottom line is if u dont want to take the risk dont do it..

    trog
  18. Solaris17

    Solaris17 Creator Solaris Utility DVD

    Joined:
    Aug 16, 2005
    Messages:
    17,133 (5.21/day)
    Thanks Received:
    3,543
    Location:
    Florida
    you can get design blueprints/schematics of the voltage regulation chips on the cards and the pcb layout..then you can just kinda figure it out from their because it gives you all the grounds resistances of certain resistors..and you just kinda put it together test it out then wright a guide.

    stickied.
    Random Murderer says thanks.
  19. DaMulta

    DaMulta My stars went supernova

    Joined:
    Aug 3, 2006
    Messages:
    16,117 (5.48/day)
    Thanks Received:
    1,454
    Location:
    Oklahoma T-Town
    More voltage = able to clock it higher
  20. reverze

    Joined:
    Dec 28, 2007
    Messages:
    1,368 (0.56/day)
    Thanks Received:
    131
    ...I want my VF900 now :banghead:
  21. reverze

    Joined:
    Dec 28, 2007
    Messages:
    1,368 (0.56/day)
    Thanks Received:
    131
    Hmmm,

    who sais...source?

    I wanna read !
  22. sneekypeet

    sneekypeet Unpaid Babysitter Staff Member

    Joined:
    Apr 12, 2006
    Messages:
    21,511 (7.05/day)
    Thanks Received:
    6,037
    hey Random WTF is the copper cooler on the card in the picture for?
  23. tigger

    tigger I'm the only one

    Joined:
    Mar 20, 2006
    Messages:
    10,183 (3.31/day)
    Thanks Received:
    1,399
    extra cooling for the regs i guess,its on the other side of the board to them.
  24. sneekypeet

    sneekypeet Unpaid Babysitter Staff Member

    Joined:
    Apr 12, 2006
    Messages:
    21,511 (7.05/day)
    Thanks Received:
    6,037
    I know but mine is never even the slightest warm to the touch....being an ex-1950PRO owner I checked it !
    Last edited: Jan 2, 2008
  25. Random Murderer

    Random Murderer The Anti-Midas

    Joined:
    Dec 6, 2006
    Messages:
    6,420 (2.28/day)
    Thanks Received:
    1,144
    Just an extra ramsink I had laying around, figured I would put it opposite the VRegs.
    blacktruckryder says thanks.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guest)

Share This Page