The slider controls, in the Energy Saver control panel, affect only what happens when the computer is left unattended, also known as an idle state.
Note: The button highlighted in the Energy Saver Control panel says "Idle Sleep."
This panel only controls what happens when the computer is left untouched for the time you specify in this panel. However, if you choose sleep from the Special menu, or from the dialog presented when you press the power key, you are manually ordering the computer to go to sleep, so these settings would be ignored.
The Energy Saver control panel is actually an application, which serves as a front-end to the Power Manager, which controls the power management hardware. Disabling Energy Saver will change the state of any of the user-definable settings, as these settings reside in the Energy Saver Preferences file.
When Energy Saver calls the Power Manager with the settings, the Power Manager writes 2 values to PRAM, the sleep timeout and hard drive sleep time as numbers from 0-255. Each number is an increment of 15 seconds so to sleep in 30 minutes, 120 is stored in PRAM. These are the only settings saved to PRAM.
Note: These are just the length of time, and not whether the system or hard disk sleep has been disabled (set too never).
Disabling Energy Saver will cause the system to sleep in about 1 hour, if the system were set to never sleep. This is true if booting with extensions off, or just removing the Energy Saver control panel. If the system were set to sleep at some specified time that will still be honored.
Also, the monitor will not dim, if the system is booted with extensions off or the Energy Saver control panel disabled. The monitor will be turned off when the system sleeps.
There are no user-definable settings for the sleep state, only for what happens when the computer is idling or waking. Putting the computer to sleep manually will always lead to the same behavior:
On all computers:
- the processor will go into a low-power mode
- video output will turn off, as a result the display may turn off as well
- the Apple-supplied hard disk will spin down
On PowerBooks:
- the Ethernet ports(s) will turn off *
- the PCMCIA port(s) will turn off *
- the Serial port(s) will turn off *
- the built-in modem will turn off *
- the ADB or USB connection will only respond to the power key on an external keyboard
- the CD or DVD drive will spin down
- Audio input and output will turn off
On some desktop and mini-tower computers:
- Audio input and output will turn off
- The CD or DVD drive will spin down
* Note: Network connectivity will be lost during the sleep state on a PowerBook. If you wish to use file sharing or remain connected to a dial-up internet connection, consider setting the Energy Saver control panel to sleep = never, setting separate timing to spin down the hard disk, and dim the display when not in use.
To wake a PowerBook, which is in sleep mode, from an externally connected keyboard, you must press the power key on the external keyboard or any key on the built-in keyboard. Other keys on the external keyboard will not wake the PowerBook from sleep in this power-saving state. If the PowerBook is not completely asleep, but has simply spun down the hard drive and dimmed the display on idle, pressing any key on either keyboard will "wake" the computer.
On computers running Apple Video Player or Apple DVD Player as the front most application, the computer will not go to sleep when left idle. Other applications, such as some fax software, will also prevent the computer from going to sleep when the Idle Sleep timeout value is reached.