MacOS – MacBook Pro high CPU with external monitors

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I recently ordered two 4K monitors (LG 27UD88). I connected them using Mini DisplayPort to DisplayPort Adapter cable to my MacBook Pro.

When I have the monitors connected, the CPU load is very high with fans running at 5500-6000 RPM and a processor temperature of 54°C. This does not seem healthy to me. It's kernel_task which is using absurd amounts of CPU (sometimes spikes up to 600%)

Things I've tried so far

  1. Before I used to have a high CPU load as well (with the additional monitors connected), but that got resolved after following the instructions in this article, CPU usage is too high with Yosemite and an external monitor, kernel_task spikes to 600%+.

  2. Disabling X86PlatformShim.kext

  3. Resetting the SMC.

This all seems very odd to be. I have a maxed out MacBook Pro which can't handle two monitors?

Here is the system configuration:

MacBook Pro (Retina, 15-inch, Mid 2015)
Processor: 2,8 GHz Intel Core i7
Memory: 16 GB 1600 MHz DDR3
Graphics: AMD Radeon R9 M370X 2 GB
          Intel Iris Pro 1536 MB
Storage: 500GB Flash Storage

Information from sensors:

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UPDATE #1:

Here is the information on the GPU load. It seems that the GPU load is high, but that the processor of the AMD Radeon is not used. I'm currently looking into this, if you have any suggestions on how to make more use of the AMD Radeon GPU please do.

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I do have Automatic graphics switching turned off (this should increase high-performance graphics).

Also the system preferences tell that the AMD Radeon is being used for the external display. Though the iStat data suggests otherwise.

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Update #2:

I've installed gfxCardStatus and put it to discrete only. Looks like the AMD Radeon GPU is actively being used. This does not make a difference.

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Update #3:

I've ran iStat for a while now. Looks like the CPU has many spikes, even up to 90 degrees. This would obviously trigger the fans to start blowing (also the MacBook itself feels hot near the processor). Looks like the average temp at the moment is 70 degrees.

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Here is the CPU frequency:

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Best Answer

Folks this is an image of my fans before I had them cleaned.

Clogged fans with dust in my MBP

I faced the very same issue that you guys are facing and based on input from another forum decided to get my 2016 MPB fans cleaned out. This made an immediate impact where when I connected my external display to the MBP.pre-cleaning, it would overheat causing the fans to spin at 6000 rpm or thereabout and the kernel_task would eat up 500%-900% of the CPU rending the system unusable. This simple cleanup of the fans has allowed me to connect the monitor with no kernel panic anymore and even though the fans run around 5000 rpm now the CPU and GPU are running around 10 degrees cooler now.

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