Réponse à : « kernel_task takes up 500% of my CPU when plugging in external monitor »@danj and @mattscheurich I'm also facing the issue. I have a 2K display attached to: MBP mid 2015 Processor: 2.5 GHz Intel Core i7 Memory: 16 GB 1600 MHz DDR3 Graphics: AMD Radeon R9 M370X 2048 MB, Intel Iris Pro 1536 MB The CPU goes bonkers and kernel_task remains at +400%. Unplugging the Dell 2K display immediately settles it down. I'm using plain HDMI cable for the display, it's not a thunderbolt. I'm not sure how a damaged Thunderbolt chip can be a cause here because I'm using HDMI?