Toshiba Satellite C640 - Manual (Page 98)

User’s Manual 4-31
Operating Basics
Heat Dispersal
To protect from overheating, the CPU has an internal temperature sensor. If
the computer’s internal temperature rises to a certain level, the cooling fan
is turned on or the processing speed is lowered. You can select whether to
control the CPU temperature by turning on the fan first, then if necessary,
lowering the CPU speed. Or, turns on fan first, if necessary lowers CPU
processing speed earlier than at Maximum Performance Mode for long
battery life. These functions are controlled within the Power Options.
When the CPU temperature falls to a normal range, the fan is turned off
and the CPU operation returns to standard speed.
If the CPU temperature reaches an unacceptably high level with either
setting, the system automatically shuts down to prevent damage. Data in
memory will be lost.