HP EliteBook 850 G1 Notebook PC - Manual (Page 24)

Component Description
(2) Service door release latch Releases the service door on the computer.
(3) Service door release lock Locks the service door.
(4) Vents (3) Enable airflow to cool internal components.
NOTE: The computer fan starts up
automatically to cool internal components and
prevent overheating. It is normal for the internal
fan to cycle on and off during routine operation.
(5) SIM slot (select models only) Supports a wireless subscriber identity module
(SIM). The SIM slot is located inside the battery
bay.
14 Chapter 2 Getting to know your computer