CPU Usage

Discussion in 'Mac Basics and Help' started by simontarr, Nov 21, 2006.

  1. simontarr macrumors 6502


    Sep 4, 2006
    Hi All,

    I have a Core 1 Duo iMac 2GHz, and have a quick question about the CPU usage. Because I have two cores, should the CPU usage read a figure out of 200% or does it combine the two cores into 100%?

    The reason I ask is that even on really CPU-Intensive tasks, like HandBrake, it will hover on about 87% (In Activity Monitor and iStat Pro Widget) but every so often, I notice go above 100% (sometimes it reaches 157%, before going back down again) Is this because the application isn't 'dual-core' optimised?

    I would like to know because it seems like I'm only ever using 1 core.

    Thanks for you help guys/gals.
  2. bousozoku Moderator emeritus

    Jun 25, 2002
    Gone but not forgotten.
    You can use the CPU usage window in Activity Monitor to graphically show you an estimate of what each processor or core is doing.

    Did you see this thread?
  3. robbieduncan Moderator emeritus


    Jul 24, 2002
    200% would be both cores working flat out. 100% is one core working flat out (or not, could be both cores working 50%). A single-threaded app can never use more than 100% of the CPU. A multi-threaded app can use more than 100%...

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