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Energy Saving Options for Macs

written by: Mike Metzger•edited by: Bill Bunter•updated: 5/5/2010

Trying to save the environment or just trying to save on the electricity bill? If you're one of the millions to own a Mac, there are some simple things you can do to optimize your computers power usage.

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    Trying to save a few bucks on the monthly power bill? If you've got a Mac there are many simple options available to reduce the overall cost of using your computer.

    The first task is to open the System Preferences and click on the Energy Saver icon. Depending on whether you have a desktop or a laptop, you'll have a couple options available. All Mac computers have the following options:

    • Put the computer to sleep when inactive for...
    • Put the display(s) to sleep when inactive for...
    • Put the hard disk(s) to sleep when possible

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    Put the computer to sleep...

    For most users, their computer does not need to be active and running all the time. This is a common point of energy waste for any computer, whether PC, Mac, Desktop, or Laptop. This option will put your computer to sleep automatically assuming there are no programs running that require it to stay awake. The effect is the same as if you manually clicked the Apple logo and chose "Sleep".

    The best option here is to consider the amount of time you'd typically be away from your system before returning. If you are often distracted from a computing task (by kids, pets, the doorbell, and so on,) setting this value to 20-30 minutes will be sufficient. It will give you energy savings but not require a waiting period to wake up the computer. If your workload requires, it is easy to set this value further out.

    Depending on the roles your computer plays, you may even consider disabling the sleep option entirely. I have one Mac Mini acting as an iTunes media server which remains on all the time (for the AppleTV in the bedroom.) Consider the workloads and adjust accordingly.

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    Put the display(s) to sleep

    On every Mac the display accounts for a considerable level of power usage - this is true whether it is a Mac with an integrated screen (iMac or the laptop lines), a separate screen only (Pro and Mini,) or both (Laptop with an external screen.) This option will simply disable the screen or the signal going to it, depending on the screen type.

    My general rule of thumb is again to determine how long I will watch a screen without typing or moving the mouse. This can include reading a web site, watching a video, listening to a podcast, etc. I will usually set this value to 10 or 15 minutes as this fits my usage best. Other people I've worked with can easily set it to 5 minutes and have no issues at all.

    It's worth noting that some programs will automatically keep the screen awake for you regardless of setting - Front Row will do this if you're actually watching a show or movie.

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    Put the hard disk(s) to sleep

    This one is simple - unless your computer needs to be instantly responsive (mainly, it's acting as a network server in any high-load environment) keep this box checked. It does cause a slight delay when returning to use the computer, but it does save significant levels of energy, especially on laptop systems.

    Even in the situation of my Mac Mini media server this option makes sense. I'm not constantly using the hard drives even though I leave the computer enabled. This allows me to save some power usage while still keeping the data easily available.

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    Laptop Computers

    It's worth noting that if you have a laptop, you have another option available. In addition to the "Power Adapter" setting, you also have the options for behavior based on the "Battery" setting. This means you can easily have separate behavior based on whether your computer is plugged in - just select which of the four options makes the most sense for you. On my MacBook Pro, I have "Better Battery Life" selected (Note, this is analogous to the "Better Energy Savings" option when plugged in) and works beautifully for most of tasks.

    There is also an Options section that mostly defines how the computer will behave in certain circumstances. For example, if you select the "Better Battery Life", there is a setting that will slightly dim the display preserving a bit more battery life.

    One final note of advice - if you're trying to reduce power usage and you have laptop computers, make sure to unplug them in the evening if they are not being used (ie, are asleep.) The power adapter will draw electricity even when the battery is fully charged, wasting energy further.