I have it both on a MacBook Air 2011 11" and a MacBook Pro 2015 13"

This is a bug in 16.10
It did not exist in 16.04
It appears to be for ALL 16.10 kernels to date, ie. from 8/27/2016 onwards

MacBook Pro:
uname --kernel-release --kernel-version
4.8.0-27-generic #29-Ubuntu SMP Thu Oct 20 21:03:13 UTC 2016

MacBook Air:
uname --kernel-release --kernel-version
4.8.0-27-generic #29-Ubuntu SMP Thu Oct 20 21:03:13 UTC 2016

It is triggered by not high temperture but some flawed conclusions
Once kidle_inject launch they eat 50% of available cpu power forever

Perhaps it is triggered by watching flash video from cnn in Chromium

syslog when triggered:
grep powerclamp /var/log/syslog
Nov 17 10:04:22 c89 kernel: [82843.821614] intel_powerclamp: Start idle 
injection to reduce power

reading temperatures on MacBook Pro:
sensors | egrep "^(Right|Core|TCGC|TB0T)"                  
Core 0:         +69.0°C  (high = +105.0°C, crit = +105.0°C)
Core 1:         +68.0°C  (high = +105.0°C, crit = +105.0°C)
Right Side  : 3097 RPM  (min = 1299 RPM, max = 6199 RPM)
TB0T:          +36.8°C  
TCGC:          +71.0°C  
- the TCGC is GPU which is what supposedly should trigger about 85 °C

Fix to next reboot: 
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1389077/comments/6
rmmod intel_powerclamp

Across reboot fix:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1389077/comments/12

Just another bug in i915. Don’t expect a fix anytime soon, so just
disable if it happens to your computer

** Changed in: linux (Ubuntu)
       Status: Incomplete => Confirmed

** Summary changed:

- kidle_inject overly onerous, fans never used on MacBookPro12,1
+ i915 intel_powerclamp consuming 50% cpu kidle_inject

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https://bugs.launchpad.net/bugs/1640000

Title:
  i915 intel_powerclamp consuming 50% cpu kidle_inject

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