Kill-A-Watt readings

Discussion in 'MacBook Pro' started by Zel, Aug 22, 2007.

  1. Zel macrumors regular

    Jul 7, 2007
    The MBP with the older large 85W magsafe. I thought that meant 85W DC output to the laptop, which implies something between 100 and 120W intake from AC accounting for inefficiencies.

    We could not know until we test it with a real meter. Well I've gotten one and it's astonishing.

    LED backlight at 3/4ths, charging battery at 80%.

    sitting at desktop, usage is 45 watts!!

    Run up the CPU to maximum (through running two threads of yes into dev/null) usage is only 78 watts!!

    I might be able to get it higher by burning a dvd or using the graphics card, but with just cpu it only gets to 78 watts intake from AC, which accounting for some sort of inefficiency means the laptop is only eating under 70 watts itself. wow.

    Any more experiments I need to run? (I'm off now to try my Dell 2407FPW)
  2. squeeks macrumors 68040


    Jun 19, 2007
    yup, i discovered the same thing, the power supply is rated for what it can handle

    my 600watt psu in my PC only uses about 250-300 watts for normal everyday stuff and about 350 with CPU at full load

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