CDU comes with Energy Star mode enabled. This means that your machine will automatically shut down after 60 minutes of inactivity, except during business hours (8 am to 6 pm). Energy Star also dims your monitor after 30 minutes of inactivity to save energy and your wear and tear on your screen.
To change the default Energy Star settings, click on the Energy Star icon in the icon window on the left. Then make sure the On/Off switch in the upper right corner is in the correct position (On means Energy Star features are enabled, Off means they are disabled).
1. Set the brightness you want the monitor to be dimmed in the "Dim to %" box. 0% fully dims the monitor. 25% provides nearly as much power saving and proctects your monitor while still enabling you to read your screen.
2. Adjust the "Auto-Dim Screen Delay" to a value that represents the amount of idle time you want to wait before your monitor is dimmed.
3. Adjust the "Auto-Shutdown Delay" to a value that represents the amount of idle time that must pass before the machine is turned off.
4. If desired, check the "Don't Auto-Shutdown between" box and set the hours during which you want the Macintosh to not be turned off.
 
Note: If your machine does not support "soft power-down" the Auto-Shutdown Delay items will not be displayed.
What Happens at Shutdown?
Compliant with the EPA's Energy Star controlling device requirements, CDU "bookmarks" your system when it shuts down due to inactivity. Bookmarking means that whatever applications and documents were open when the machine went inactive will be restored when it is restarted. In other words, when you turn your Macintosh back on, the applications and documents you had open will be reopened automatically for you.
CDU (in conjunction with the Macintosh operating system) does the following when inactivity causes it to shutdown the computer:
• all open documents will be saved (previously unsaved documents are put in a "Work in Progress" folder on the desktop marked with the day's date )
• any dialogs or alerts that appear will be dismissed
• any removable media is ejected
• any warning condition is taken care of before shutdown (e.g., if the machine is spooling a long document to the printer, this is completed first)
• network backups will be correctly completed before shutdown
CDU’s default is to preserve and restore all active user data, even if it is unsaved. During an automatic shutdown, CDU performs a save on all documents that have unsaved changes.
This may not be what you want CDU to do. You have two other options: (1) deselect the auto-save option so that no changes are saved—this means CDU will stop the shut down process if it encounters any documents that have not been saved; or (2) close any documents that you don’t want saved before leaving the computer at the end of the day. In general, it is a good idea to save often and not leave unsaved documents hanging around when you walk away from your machine. Power failures and unsuspecting coworkers could easily lose information in such cases.
