get more vcore under load: vdroop pencil mod (pics)

Discussion in 'Overclocking & Cooling' started by graysky, Jun 3, 2007.

  1. graysky

    graysky Gawd

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    This is one of the easiest mods you can do to your P5B-Deluxe (and probably any P5B although I haven't tested it on any model but the Deluxe) to help you get higher voltages under load conditions and also lower your idle vcore; it is particularly useful for people wanting to get more juice to feed their o/c'ed chip.

    Background
    As you know, the P5B-Deluxe (and others in the P5B family) has a vdroop built in for some reason (protect processor maybe, I dunno). Vdroop is the term used to describe the voltage drop between idle and load conditions.

    Try it yourself right now: (assuming you have your vcore manually set in your BIOS) load up CPU-Z and see what it's reporting as your idle vcore. Now load up a few instances of orthos and have a look. For example, before the mod, mine dropped from 1.280v (idle) to 1.232v (load) which is -0.048v! After you do the "pencil mod" it should drop by a very small amount or none.

    The "Pencil" Mod

    What do you need? A soft pencil. Look for one with a 2B rating on it. Standard pencils are HB. HB pencils will work, but the softer the pencil lead, the better the results. You can find a 2B pencil at most any office supply store (staples, officemax, etc.); they are usually in the art or drafting section (aisle #7 for my staples). I got one in 4 pack for under $3.

    Now, either unplug or switch off your power supply so the LED has gone out and simply shade (gently draw with the pencil back and forth) over the correct surface mount component (it's a resistor maybe?) -- refer to the pictures below... it's the one with the yellow arrow pointing to it.

    [​IMG]
    [​IMG]
    You can see on the zoom where I colored over the right one.

    NOW, boot into Windows and repeat that exercise where you measure the load and idle vcore. Mine went from a drop of 0.048v before I did the mod to a drop of 0.008v after the mod. These are both @ a BIOS vcore of 1.3250v.

    I recently lowered the BIOS vcore to 1.2625v and now I have NO vdroop at all: idle is 1.232v and load is 1.232v, and the system is stable to 2x orthos for over 6 h!

    Undoing the "Pencil" Mod

    You can undo this very easily with a little alcohol and a few q-tips. It is 100 % reversible.

    If you found this useful, please post your before/after results in this thread.

    Enjoy!
     
  2. BillParrish

    BillParrish [H]ardness Supreme

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    Your guess is correct. There is a very good reason droop exists.

    http://www.thetechrepository.com/showthread.php?t=126


    Anyone considering the "pencil" mod should read the above link, you can skip the math the text tells you what is going on and why.

    Its your stuff, do what you want.


    if you are going to try this, get an artist quality pencil, "normal" pencils now are mostly colored clay cores, you want a graphite core if you can find them.
     
  3. unclewebb

    unclewebb [H]ard|Gawd

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    graysky: Thanks for the pics and thanks Bill for the technical reasons behind vdroop.

    I think most processors will probably survive this mod. The only real advantage I see is being able to lower your idle voltage by about 0.05 volts which reduces power consumption at idle by 10 watts. I should be able to cover the cost of a 2B pencil in a year or two. :D
     
  4. unclewebb

    unclewebb [H]ard|Gawd

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    I couldn't resist. My motherboard was out getting a new Tuniq and there was a pencil with a 2 just sitting there so what the hell, I did my first volt mod.

    Now that I've just re-read the directions it turns out I was supposed to be using a 2B pencil. The one I had handy was a 2H. Hmmmm.

    I used to run 1.424 volts at idle and the that would droop down to 1.392 volts when running Orthos. From a droop of 0.032 volts, I've cut that in half to 0.016 volts of droop. Now running Orthos it only drops down to 1.408 volts.

    My AMD64 on a Gigabyte board used to add about 0.05 volts at full load so I figure reducing vdroop can't be that bad a thing. Thanks for the tip graysky. It works, even on my v1.03 P5B Deluxe! :D
     
  5. graysky

    graysky Gawd

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    50 mV = 10 watts? It's been a while since I had physics so please explain the math behind that statement. Thanks!

    Here's some math to consider: say power costs are $0.15 per kWh. If you save 10 W (0.01 kW), and your machine runs 24/7 and is idle for say 90 % of that time. You're saving $0.0324 per day or about $1 per month. My pencil set cost just under $3 so in September, it will be paid off :)
     
  6. graysky

    graysky Gawd

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    2H? That isn't a very good one. Have a look at this wikipedia article on pencil lead: 2H is about 60 % graphite while 2B is about 74 %. You can undo your mode with a q-tip and some rubbing alcohol if you wanna get a 2B and repeat. As I said in my post, I have no vdroop after doing it.
     
  7. KD28

    KD28 [H]Lite

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    Wouldnt an advantage be that this would allow you to drop your vcore a bit (since you have less vdroop you'd need slightly less vcore for stability) and thus drop your temps a bit?
     
  8. unclewebb

    unclewebb [H]ard|Gawd

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    I didn't want to get in trouble from BillParrish so I'm quite happy with the results of cutting my vdroop in half. I have my computer plugged into a Kill-a-Watt meter so I'll play with the core voltage tomorrow and see if decreasing it by 0.05 volts really does save 10 watts.

    KD28: With less vdroop you could lower your bios voltage and still maintain your full load voltage. At full load, same voltage equals same heat but at idle you would have less voltage which equals less heat but heat is never a problem at idle so it doesn't make any real world difference. If you can save a few watts of power it might add up to cover the cost of a good pencil though.

    Edit: For testing purposes I dropped my idle voltage from 1.424v to 1.376v or a drop of 0.048 volts. That reduces power consumption by 5 watts at the plug.
    I was hoping for more :D