Toshiba Satellite Pro C870 - Manual (Page 105)

the processor speed first, then if necessary turning on the fan. Both of
these functions are controlled through the Power Options.
When the processor's temperature falls within normal range, the fan will be
turned off and the processor operation returned to its standard speed.
If the processor's temperature reaches an unacceptably high level with
either setting, the computer automatically shuts down to prevent any
damage. In this instance all unsaved data in memory will be lost.
User's Manual 4-47