27" iMac & 27" Cinema LCD - Power Consumption / Heat

Discussion in 'iMac' started by Mactopus, Dec 6, 2010.

  1. Mactopus macrumors newbie

    Dec 6, 2010
    Hi all,

    I'm speccing out a new system and trying to minimize power consumption and more importantly heat. Hopefully somebody can share some info here that will be useful for other people too.


    The Apple LED Cinema Display (27" flat panel) [1] is reported to draw approximately 90 W (Watts) power when in use at close to full brightness (and when not charging a MacBook). This is according to multiple detailed reviews: [2] [3].

    The Apple iMac 27" [4] is reported to draw approximately 1 W - 2 W at "Sleep", 35 W - 40 W at "Idle" and 140 W - 160 W at "load" according to multiple detailed reviews: [5] [6].

    [1] http://store.apple.com/us/product/MC007LL/A?mco=MTkwMzg0OTE
    [2] http://reviews.cnet.com/lcd-monitors/apple-led-cinema-display/4505-3174_7-34184192-2.html
    [3] http://www.anandtech.com/show/3946/apple-27inch-led-cinema-display-review/8
    [4] http://store.apple.com/us/configure/MC510LL/A?mco=MTg1ODA3Nzg
    [5] http://reviews.cnet.com/desktops/apple-imac-27-inch/4505-3118_7-33783915-2.html
    [6] http://thetechjournal.com/electronics/computer/apple-imac-review.xhtml


    Question 1: In these reviews, does "Idle" for the iMac 27" mean the screen is off but the computer is not asleep? Because otherwise I can't figure how it could draw so little power (<50%) compared to the Cinema display of the same size when it has to be a monitor AND a computer at the same time. You would think it would be more (display + HD + CPU, etc.).

    Question 2: How much power does the iMac 27" draw with the screen on, but not doing very much work?

    Question 3: How much of the power used by either the Cinema display or the iMac is heat and how much is light? I.e. how efficient is the LED backlighting, etc.? Does the display pulling 90 W generate as much heat as a 90 W incandescent light bulb?

    Question 4: How close do you have to be to the front of the Cinema display or iMac 27" in order to feel heat coming off of it? Do you notice either in day-to-day use? If in a small room, does using either generate perceptible heat?

    Question 5: Any other information or suggestions on these topics of energy and heat are welcome!

    Thank you!
  2. Btom macrumors 6502a

    Nov 19, 2009
    I've just checked and the 27" iMac is specified at 365W of continues power on the Apple own site and probably for a reason. I'd use this number (plus ~20%) and risk a nice surprise rather than a number from a random review and have a nasty one.

    Tom B.
  3. i Smack macrumors member

    Nov 1, 2010
    Minimal heat comes off the 27" iMac. I've only had mine a month, but I was gaming on it for pretty much 8 hours straight last Sunday and only noticed the top rear was a bit hot.

    But yeah, I wouldn't expect to heat a small room with it lol
  4. peskaa macrumors 68020


    Mar 13, 2008
    London, UK
    My 27" ACD doesn't put out much heat at all. I've had it running for hours, and there's a small slightly warm patch at bottom left, but that's it - whereas the older 23" ACD in the house gets very hot to touch over large areas.

    My experience with the 27" iMacs is that the iMacs, obviously, get warmer. The vent along with top edge can get quite toasty.

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