Adjust Whether a Mac Restarts Automatically on System Freeze
Modern Macs with new versions of Mac OS (or Mac OS X) default to automatically reboot themselves upon a system freeze. This is a troubleshooting feature that aims to prevent average users from having to initiate a forced restart, since the Mac would simply restart itself if a system freeze were to occur.
While most users should not adjust this setting away from the default auto-restart option, some advanced Mac users may wish to toggle or disable the automatic reboot on freeze function of Mac OS X for some reason or another.
Check if the Mac Will Restart Itself Automatically
Launch Terminal and enter the following command string, the systemsetup command requires sudo to access:
sudo systemsetup -getrestartfreeze
You’ll either see one of two reports, indicating the status of the feature:
Restart After Freeze: On
Restart After Freeze: Off
Again, the default Mac setting now is to be “On” – it is highly recommended to leave that setting enabled as is and not adjust it.
Adjusting the Automatic Mac Restart Upon Freeze Feature
If you’re advanced user and you wish to toggle the auto-restart on freeze feature, the following command syntax will do so. Adjust the ‘on’ or ‘off’ component of the command to achieve the desired effect:
Turn automatic restarting upon freeze on:
sudo systemsetup -setrestartfreeze on
Turn automatic restarting upon freeze off:
sudo systemsetup -setrestartfreeze off
Keep in mind if you turn this feature off, an unattended frozen Mac will stay frozen at whatever is on screen for however long it takes a user to come an force the computer to reboot, if not for some other power event taking place. This is one of many reasons why the average user should leave the setting turned on.
Even with the automatic restart on freeze feature left enabled, sometimes, a frozen Mac can be so stuck that it requires forcibly rebooting to get the computer to behave again.
Note this setting was actually contained in the System Preferences for a while in earlier versions of OS X, but newer versions of Mac OS X removed the option and instead simply default to having the feature on.