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Thread: Abit AI7 (Vdimm) Mod?

  1. #1
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    Question Abit AI7 (Vdimm) Mod?

    Im currently feeding maximum voltage available in AI7 mobo (3.2V) for my KHX PC3000 sticks, which naturally isnt enough, for those Winbond BH-6 chips. I need atleast 3.45V to run these sticks at 260MHz 2-2-2-5 speeds.

    So does anybody know, how to vdimm mod this mobo?

    Thanks

  2. #2
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    Bump^^

    Does anybody know where to measure current VDD voltage?

  3. #3
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    im also interested in this. i looking to get this board for a 2nd box. and a vdimm over 3.2v would be a must. somebody needs to find out what regualtor its using so they can determine how to do the mod. hopefully soon somebody will figure it out
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  4. #4
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    Solved it by my self

    For higher memvolts, you need PSU with "trimmed" 3.3V line to get more voltage for memory.

    Solder 10ohm vr, on the other end (closer to NB) of R153 resistor, and the other wire from vr to ground.
    Do NOT unsolder R153, like R50 resistor in IC7 / IS7 mobo.

    When using 10ohm vr, actual VDD is ~ -0.04V from 3.3V line.
    (mine: 3.3V line = 3.43V, Vdimm = 3.38V).

    You can measure current Vdimm voltage from upper (right) corner of mobo, from mosfet Q11 or Q13 lower leg.

    No pics sorry
    Last edited by The Stilt; 12-03-2003 at 03:01 AM.

  5. #5
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    check these pics here maybe that will help out.
    Last edited by esoteradactyl; 12-03-2003 at 11:44 AM.
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  6. #6
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    nice i'm getting Ragnorak/Mjollnr to mod an Antec TC PSU's 3.3v rail upto 3.75v for me for this purpose

    are the vdimm measuring points the 2 black square boxes in the lower left of this pic http://www.fileshosts.com/pentium4/D...b/AI7_064.html ?

    do you mean just psu's modded 3.3v rail would not work, you need to mod the board too ?
    Last edited by eva2000; 12-03-2003 at 03:50 PM.
    ---

  7. #7
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    Seems abit moved well away from the IC7 design on this board.

    Does Vref track well with the vdimm mod in place?
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  8. #8
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    do you mean just psu's modded 3.3v rail would not work, you need to mod the board too ?
    yes you need to mod the board and your psu. raising the 3.3v rail will do nothing without the board being modded. the resistor on the board wont allow you to go any higher than 3.2v.
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  9. #9
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    Originally posted by eva2000

    are the vdimm measuring points the 2 black square boxes in the lower left of this pic http://www.fileshosts.com/pentium4/D...b/AI7_064.html ?
    No. You can measure vdimm from those mosfets, near atx connector.

  10. #10
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    Originally posted by esoteradactyl
    yes you need to mod the board and your psu. raising the 3.3v rail will do nothing without the board being modded. the resistor on the board wont allow you to go any higher than 3.2v.
    thanks confirmed just 3.3v rail psu mod won't work ... had 3.3v between 3.4-3.6v and vdimm still stuck at 3.2v heh

    anyone got pics of this mod ?
    ---

  11. #11
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    Here is a pic of that mod:


    Wire is actually soldered only the other end of resistor R153, not to MC245 condensator. Guy who did that mod, must have little shaky hands...

  12. #12
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    thanks mate... guess i gotta learn how to soldier after Xmas
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  13. #13
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    The Stilt

    What volts can you get out of it now??


    Dont even ask where i've been!!!

  14. #14
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    Originally posted by Tedinde
    The Stilt

    What volts can you get out of it now??
    When the vr is set to 10ohms, VDDR is PSU +3.3V line, ~ - 0.04V.
    After the mod, there is no limit for maximum voltage, if I set PSU +3.3V line to 3.6V VDDR is ~ 3.55V

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    thanks
    Last edited by Darkstar559; 01-06-2004 at 09:22 PM.

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    Originally posted by The Stilt
    Here is a pic of that mod:


    Wire is actually soldered only the other end of resistor R153, not to MC245 condensator. Guy who did that mod, must have little shaky hands...
    So then the 10 ohm resistor is attached to the ends of those two wires?

    And what does vr mean in this context: "Solder 10ohm vr"

    Thanks!

  17. #17
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    Originally posted by nleahcim
    So then the 10 ohm resistor is attached to the ends of those two wires?

    Yep.

    And what does vr mean in this context: "Solder 10ohm vr"

    vr = Variable resistor

    Thanks!

  18. #18
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    Originally posted by The Stilt
    OK one other thing - do you know how much current will be running through this potentiometer? Well - actually the wires connecting the potentiometer. Since the parts I'll be soldering to are so small - I'd like to use as fine of wire as possible.

    also - does vdimm increase or decrease when resistance is increased? Thanks!
    Last edited by nleahcim; 01-06-2004 at 07:52 PM.

  19. #19
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    Originally posted by nleahcim
    OK one other thing - do you know how much current will be running through this potentiometer? Well - actually the wires connecting the potentiometer. Since the parts I'll be soldering to are so small - I'd like to use as fine of wire as possible.

    also - does vdimm increase or decrease when resistance is increased? Thanks!
    Dunno about the current, but I used wire with 1mm diameter so any wire should be able to handle the current.

    I found that 10 ohm resistance works best, because AI7 is capable to give 3.2V Vdimm by default. (Vdimm is ~ -0.04V from 3.3V rail, when 10ohm resistor is used). Lower resistance, causes that mobo wont boot.

  20. #20
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    So it could be made using only 10ohm fixed resistor Thats good to hear cos the electronics shop at my town didnt have 10 ohm VRs. Now all I need to do is find 10ohm resistor somewhere(where did I put my old psu...)
    cool cool cool!

  21. #21
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    Anyone wanna fix that broken pic link so I can see how it's done?

  22. #22
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    it's better now, thanks.

  23. #23
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    Thanks for info I will mod mine.Can I use grabbers.
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  24. #24
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    Might try it this night cos Im gettin so bored! Hope I dot fry the mobo
    cool cool cool!

  25. #25
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    Didnt try it after all cos after looking at the resistor I realized that I need much smaler tip for my soldering iron. Well maeby tomorrow
    cool cool cool!

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