Sony PCG-F540 Primary User Manual page 56

When you use a battery as the source of power for your computer, you
can take advantage of power management settings to conserve battery
life. In addition to the normal operating mode, which allows you to turn
off specific devices, your computer has three distinct power saving
modes: System Idle, System Suspend, and System Hibernation. When
using battery power, you should be aware that the computer
automatically enters System Hibernation mode when the remaining
battery charge drops below 5 percent, regardless of the power
management setting you select.
This is the normal state of your computer when it is in use. The green
power indicator light is on in this mode. To save power, you can turn off a
specific device such as the LCD or the hard disk.
This mode is convenient if you do not need to use your computer for a
brief period. The hard disk and video display enter a low power state,
and the CPU clock and processor stop. The power indicator light is umber
in this mode.
Press Fn+S, or use the PowerPanel utility.
Press any key.