Silicon Graphics POWER CHALLENGE User Manual page 41

Cooling System
The vaned rotor is in contact with the System Controller and changes speed
to provide more or less airflow, depending on the temperature of incoming
air (see Figure 2-7). These changes are initiated by a temperature sensor that
helps the System Controller adjust the rotor fan for efficient cooling with the
lowest possible noise level.
If the rotary blower fan does not run after the main power is turned
Note:
on, the system will not boot. If the blower experiences a failure while the
system is running, the System Controller shuts down the server immediately
after notifying the CPU.
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