Energy saving?

Discussion in 'Mac mini' started by GiraffesAreCool, Jun 4, 2011.

  1. GiraffesAreCool macrumors newbie

    Joined:
    May 28, 2011
    #1
    How much energy does it use to wake up a mac mini from sleep? I've heard it takes up 15 minutes of energy to boot up a desktop but not sure about the mac mini.
     
  2. Big-TDI-Guy macrumors 68030

    Big-TDI-Guy

    Joined:
    Jan 11, 2007
    #2
    I've never heard of what you said before - can you cite a resource that makes this claim?

    It sounds like bunk to me - yes a computer will use a little more power on startup - but not 15% or even 15 times more - that's a tough pill to swallow. (if they did use more, you'd hear the cooling fans screaming to keep things cool every time you rebooted)

    The Mini will use more power waking from sleep then if it remains in a sleep state - but how much power the wake uses boils down to how long it's active, and whether you manually put it to sleep, or rely on a timer. Keeping the "sleep" counter as low as possible will reduce power consumption.
     
  3. lvlarkkoenen macrumors regular

    Joined:
    Apr 21, 2011
    Location:
    Utrecht, NL
    #3
    hmm.. Someone on here pointed out to me, in another thread, that his Mini uses 2W in sleep mode. He measured it himself if I remember correctly. Using 30W when booting is a good guess I think, perhaps a tad low even? One could certainly measure it. Factor in display power usage, and you'll certainly have a factor higher than 15. Ofcourse depending on if you power the display throughout the entire booting.

    Meters for this aren't particularly hard to come by. http://michaelbluejay.com/electricity/measure.html has some info on them.
     
  4. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #4
    "15 minutes of energy" is a rather vague term. it's how much energy that is used in 15 minutes. That's all it means. Booting a system will only use 15 minutes of energy if it takes 15 minutes to boot.
     
  5. lvlarkkoenen macrumors regular

    Joined:
    Apr 21, 2011
    Location:
    Utrecht, NL
    #5
    It could mean "15 minutes of energy at the level of consumption the system uses at sleep". Which is what makes sense to me, although I agree it is poorly worded.
     
  6. Big-TDI-Guy macrumors 68030

    Big-TDI-Guy

    Joined:
    Jan 11, 2007
    #6
    I'm sure the OPs source can clarify this - hence the request to cite it.

    I understand energy and power calculations - however putting that aside - the duration of a startup cycle is short enough that it'll have little impact. In addition - bootup mainly taxes the hard drive more than most other components. As of late - one of the biggest energy hogs in computers isn't really the CPU, but rather the GPU - which doesn't do much of anything during bootup.

    The short short version here is - I do not believe a PC booting up draws 15% or 15 times more power than a PC that's in an active state - already online. The first 5 seconds maybe (hard drives spinning up from a dead stop, and fans starting) - but again, that's a very short-lived load cycle.
     
  7. mr.steevo macrumors 65816

    mr.steevo

    Joined:
    Jul 21, 2004
    #7
    It appears that the mini spikes at ~33 Watts from a cold boot while consuming ~8 Watts at idle. Staying in sleep mode uses ~1.4 Watts though I don't understand what this means (1.4 Watts an hour? minute? day?). I'm not an electrical engineer or mathematician so I can't comment on this.
     
  8. lvlarkkoenen macrumors regular

    Joined:
    Apr 21, 2011
    Location:
    Utrecht, NL
    #8
    Watts per hour would make no sense at all. Watt is a unit of power, which is to say, energy per second. Those 33 Watts from a cold boot mean 33 Joule per second. (You might know Joule from calculating kinetic energy in high school?) Having a mini boot for an hour :)confused:) would consume 33 Watthour of energy. Electricity companys use kWh: 1000 Watthours. If your mini ran at 33 Watts for 30 hours, it would have consumed 1 kWh, and thus cost you about €0,20 in most European countries I guess.. Having it idle instead of in sleep mode costs you 6.6 Watts. For that to have saved a Dutchy €1, he would have to do so for about 750 hours, that is to say, more than a month.
    At the risk of digressing: taking that into consideration, electricity pricing doesn't do alot towards having consumers use less energy.

    Back ontopic. So apparently Mini uses 33 Watts during boot, and 1.4 when asleep. Assuming booting from turned down takes one minute longer than booting from sleep, you will save energy if you turn it down when not using it for 23 minutes or more. If you're going to use it again before those 23 minutes sleep is more efficient.
     

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