I noticed today a higher kernel_task CPU usage when playing audio through Thunderbolt Display from my Macbook Pro (early 2011) on OS X Yosemite. Although the CPU usage is not very high (15 - 20%), it certainly gets the fans spinning fast enough to get my attention. I would not expect this as a normal behaviour.

I've tried Spotify, iTunes and playing a YouTube video in Safari and got the same results. Here is an example when playing a song from iTunes through the internal speakers (I get the same values with headphones):

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And here is the kernel_task usage when playing the same song through my Thunderbolt Display:

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I have tried both SMC and PRAM resets, but to no avail. What could be causing this? Does anyone else experience this behaviour?

  • Same here, as soon as I select "Display Audio", kernel_task jumps to a steady 30% – xApple Feb 2 '16 at 14:46
  • I have this problem as well. I suspect it's related to the Thunderbolt display malfunctioning. Does anyone have a pair of MacBooks and a pair of Thunderbolt Displays the can use to test this? Running 10.11.3 (15D21) a MacBook Pro (Retina, 13-inch, Late 2013). – Ryan Patterson Apr 25 '16 at 16:47

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