Dell Studio 1558 (Early 2010) - Manual (Page 139)

Power (Power Settings, Power Protection Devices, and Batteries)
139
Hibernate Mode
Hibernate conserves power by copying system data to a reserved area on the
hard drive and then completely turning off the computer. When the
computer exits hibernate, it returns to the same operating state it was in
before entering hibernate.
NOTICE:
You cannot remove devices or undock your computer while your
computer is in hibernate mode.
Your computer enters hibernate if the battery charge level becomes critically
low.
To manually enter hibernate:
• Click Start → Turn off computer. Then press and hold the <Shift> key,
and click Hibernate.
OR
• Depending on how you set the power management options, you may also
use one of the following methods to enter hibernate:
• Press the power button.
• Close the display for a notebook computer.
• Press <Fn><Esc>.
NOTE:
Some PC Cards or Express Cards may not operate correctly after the
computer exits hibernate. Remove and reinsert the card, or simply restart (reboot)
your computer.
To exit hibernate, press the power button. The computer may take a short
time to exit hibernate.