Apple MD094LL/A Manuale Utente

iMac (27-inch, Mid 2010) Symptom Charts — Startup and Power 

 2010-09-09

Always run the latest available Apple service utilities to check for any abnormal value reading 
from a thermal, a voltage, or a current sensor, or from a fan speed meter. The log files may also 
report the cause of a previous shut down(s).

Collect all available info from user on shut down occurrence details: periodicity, power state 
when issue happens, running applications, running time before shutdown.

1) User-related shut downs: 

A computer shut-down event may be caused by user operation. The following shut down 
methods should not be considered as a failure, unless the power button is found to be 
defective.
•  Selecting Shut Down by choosing the Apple () menu from the upper-left menu bar and 

then choosing Shut Down.

•  Pressing and holding the power button for 10 seconds
•  Programming a timed shutdown in the Energy Saver preferences: refer to  menu>System 

Preferences>Energy Saver

Suggested troubleshooting steps are:
•  Reset the  SMC: Refer to: 

•  Check Energy Saver preferences settings: choosing the Apple () menu>System 

Preferences>Energy Saver

•  Test the Power On button for an intermittent short that would force computer to shutdown.

•  System could not succeed the standard shutdown process and had to force shutdown
•  An installed watchdog detected that an application did not respond within specified time 

(this watchdog can be enabled on Mac O X Server Energy Saver preferences)

These shut downs may be linked to system settings, devices drivers, applications, or operating 
system freezes. 

Suggested troubleshooting steps are:
•  Check the system logs and activity monitor utility for clues on the freezing process,  
•  Check for available software and firmware updates for installed device drivers, applications, 

or operating system

•  Start the system from a known-good / up-to-date bootable drive for issue reproduction.