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Undervolting a Laptop

Posted by ScuttleMonkey on from the too-late-for-my-laptop-graveyard dept.

Delph1 writes "Laptops often comes with two Achilles heels, heat and limited battery time. There are, if not cures, at least remedies to make them less obvious. By lowering the voltage to the processor you can not only drastically lower the heat dissipation, but also increase the battery time significantly. NordicHardware gives a nice walk through on the process and was able to boast 18% lower temperature and a 20% reduced power consumption."

5 of 262 comments (clear)

  1. Counter productive maybe? by squoozer · · Score: 5, Insightful

    Surely if you drop the voltage your are going to have to under-clock the processor (reasoning that to over-clock you need to increase the voltage). Most processors for laptops already throttle the processor down when under light load now-a-days which must be a great energy saving. Would under volting it really then save more or would you just end up with a laptop that is dog slow? I'm sure if it was this easy one of the big laptop producers would already be doing it as a 20% increase for basically nothing would give them a fantastic advantage.

    --
    I used to have a better sig but it broke.
    1. Re:Counter productive maybe? by NitsujTPU · · Score: 5, Insightful

      You end up with a laptop that is dog slow. You're right, most modern laptops throttle themselves effectively in order to reduce power consumption.

      What the guy is doing, however, is trying to lower the voltage consumption to the line where the processor starts to behave a little flaky, and then pumping it up just a bit over that. Processors are made in big batches, some of them just work better than others. If yours happens to be one of the good ones in the batch, you can reduce the voltage while maintaining performance (not needing to bump down the clock speed).

      If you really obsess over it, you go into the research that my roommate does, where he spends endless hours, days, and weeks tweaking processor floor plans and running them through simulators. You might hope to build a more efficient processor through all of this.

      I wouldn't recommend doing this if you're not partial to your laptop randomly hanging while you're working on it, but everyone needs a hobby.

  2. 18% -- that's really funny by Jason1729 · · Score: 5, Insightful

    How do they come off saying a reduction from 78 to 64 degrees F is an 18% reduction in temperature? The Fehrenheit scale is arbitrary and does not have a meaningful zero point.

    In celsius, their reduction is 26 to 18 degrees, a reduction of 31%

    Why not define a new scale with the same degrees but 0 degrees (new scales) = 63 degrees F. Now on the new scale they've reduced the temperature from 15 to 1 degree, a reduction of 94%....wow that's way better than their lousy 18%.

    Their number is totally meaningless.

    Also, "undervolting" is not a word.

    1. Re:18% -- that's really funny by jandrese · · Score: 3, Insightful

      Wouldn't it make more sense to compare the percentage drop against room temperature. As in:

      Pre: 24 degrees Fahrenheit over room temp
      Post: 12 degress Fahrenheit over room temp, a 50% savings!

      Obviously no amount of undervolting would ever get the processor to absolute zero, it's going to bottom out at room temperature (when reduced to 0 volts).

      --

      I read the internet for the articles.
    2. Re:18% -- that's really funny by santiago · · Score: 5, Insightful

      The correct zero point to determine the reduction in heat output would be room temperature. Compare the difference between room temperature and the high-volt processor with the difference between room temperature and the low volt-processor. After all, if it were outputting no heat at all, it would be sitting at room temperature, a 100% reduction in heat output from its initial running state.