iMac 27 screen off Power Consumption?

Discussion in 'iMac' started by Enrico, Nov 7, 2017.

  1. Enrico macrumors 6502

    Enrico

    Joined:
    Feb 6, 2007
    Location:
    Milano / Roma
    #1
    Hi guys!

    I'm debating whether to buy a NAS or use my iMac as a server running 24/7 with an HD connected to it.

    I was looking for Power Consumption figures for an iMac that has its screen powered off and Idle, since it would be running this way for the majority of time.

    Does anyone have any figures?
    I have a 27 Retina with i7, internal SSD and 12GB of RAM.
     
  2. colodane, Nov 7, 2017
    Last edited: Nov 7, 2017

    colodane macrumors 6502a

    colodane

    Joined:
    Nov 11, 2012
    Location:
    Colorado
    #2
    My 2017 (specs below) with the screen off is currently drawing 24 watts. This is measured with an external KilliWatt power meter and confirmed by the iStat Menus total power log.

    At this low power the power factor isn't stellar. Mine runs about 0.60 vs. 0.95 with the screen active.
     
  3. Enrico thread starter macrumors 6502

    Enrico

    Joined:
    Feb 6, 2007
    Location:
    Milano / Roma
    #3
    That's great! Sounds like a very low power usage, pretty much similar to a NAS...

    What do you mean with not stellar power factor? Maybe the fact that it absorbs 24 watts but in reality it wastes some of that power?
     
  4. colodane macrumors 6502a

    colodane

    Joined:
    Nov 11, 2012
    Location:
    Colorado
    #4
    The iMac power supply is a good one and incorporates active power factor correction (PFC). However, these PFC circuits don't typically operate at very low power levels. I was just pointing out that, at least on my iMac, the PFC performance deteriorates somewhere between the normal operating power with the screen on (typically 35 to 50 watts in my case) and the lower 24 watt power level with the screen off.

    This should not be a concern. All it means is that with the 0.6 PF with the screen off, the AC line current will be slightly higher than would be expected if the PF were perfect (1.0) The main point is that at higher power levels with the screen on the iMac power supply has truly excellent PF performance.
     

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3 November 7, 2017