System Fans Running Non-Stop After MacOS Sierra Installation

Some users have reported noticing that their system fans are persistently running at high speed ever since installing or upgrading to MacOS Sierra. Unfortunately this erratic behaviour appears to have been carried forward from MacOS Sierra Beta 4 to its current production edition and it doesn’t appear to be a bug.

During MacOS Sierra Beta 4 developers reported high CPU usage and persistent heat issues that appear to stem from one or a combination of the following processes that hog CPU usage and run incessently:

  1. photoananalysisd – backend process for Photos
  2. calendarAgent – MacOS Sierra Calendar’s backend that powers the Notification Center

To verify which processes are causing your Mac to overheat and force the system fans to run incessently, go to Application/Utilities, and launch the Activity Monitor application. Active processes can then be viewed under the CPU tab.

In our experience, in most cases, the biggest culprit appears to be photoanalyseid which chews up CPU usage and runs incessantly immediately after MacOS Sierra install or upgrade. It appears that this process is performing some kind of facial detection and object/image recognition indexing on your Photos library.


All this is to be able to later type words like “beach” in Photos search which will supposedly display all your photos with a beach in it without the need for you to laboriously tag all your photos individually. A new feature introduced in MacOS Sierra.

How long your CPU usage is going to be hogged with your system heat up and fans running full bore is directly correlated to how big your Photos library is.

The immediate stop-gap remedy appears to be to launch Photos which pauses the photoanalyseid process providing a brief respite for your Mac’s CPU and system fans but photoanalysid will resume what it was doing before; the moment you quit Photos.

“No”, at the moment there is no way to disable this function as MacOS Sierra’s design brief was aimed at giving Mac users this, as a ‘new feature’.

photoanalyseid works much like how Finder performs a full system indexing after installation or uprgade of any new MacOS. To facilitate quick Spotlight search results, a thorough file and folder indexing has to be performed first.

Over time, Mac users have accepted this quirk for the Spotlight gains later and in similar fashion Apple Inc is hoping the same with photoanalyseid.

The calendaragent process appears simpler to cure.

In most cases, the Calendar preference files have become corrupted as a result of the MacOS Sierra installation resulting in erractic behaviour in conjunction with iCloud Calendar syncing.

One of the common successful remedies for users who actively use iCloud Calendar syncing is to disable iCloud Calendar syncing in System Preferences/iCloud and reset Calendar by removing the ~Library/Calendars folder.

This clears all existing calendars reverting Calendar to its factory default. Re-enabling iCloud Calendar syncing in System Preferences/iCloud will bring down your existing calendars and the system will return to normal operations following completion of the iCloud Calendar sync.

You are strongly advised to backup your data before attempting the above or risk losing all your calendars forever.

If you have any constructive feedback please send your feedback on the above matters to Apple’s feedback page.

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