Thermal Management; Acpi Suspend Modes And Resume Events - Congatec COM Express conga-TR4 User Manual

7.2

Thermal Management

ACPI is responsible for allowing the operating system to play an important part in the system's thermal management. This results in the
operating system having the ability to take control of the operating environment by implementing cooling decisions according to the demands
put on the CPU by the application.
The conga-TR4 ACPI thermal solution offers three different cooling policies:
• Passive Cooling
When the temperature in the thermal zone must be reduced, the operating system can decrease the power consumption of the processor by
throttling the processor clock. One of the advantages of this cooling policy is that passive cooling devices (in this case the processor) do not
produce any noise. Use the "passive cooling trip point" setup node in the BIOS setup program to determine the temperature threshold that
the operating system will use to start or stop the passive cooling procedure.
• Active Cooling
During this cooling policy the operating system is turning the fan on/off. Although active cooling devices consume power and produce noise,
they also have the ability to cool the thermal zone without having to reduce the overall system performance. Use the "active cooling trip point"
setup node in the BIOS setup program to determine the temperature threshold that the operating system will use to start the active cooling
device. It is stopped again when the temperature goes below the threshold (5°C hysteresis).
• Critical Trip Point
If the temperature in the thermal zone reaches a critical point then the operating system will perform a system shut down in an orderly fashion
in order to ensure that there is no damage done to the system as result of high temperatures. Use the "critical trip point" setup node in the
BIOS setup program to determine the temperature threshold that the operating system will use to shut down the system
Note
The end user must determine the cooling preferences for the system by using the setup nodes in the BIOS setup program to establish the
appropriate trip points. If passive cooling is activated and the processor temperature is above the trip point the processor clock is throttled.
See section 12 of the ACPI Specification 2.0 C for more information about passive cooling.
7.3

ACPI Suspend Modes and Resume Events

conga-TR4 supports S3 (STR= Suspend to RAM).
S4 (Suspend to Disk) is not supported by the BIOS (S4_BIOS) but it is supported by most operating systems (S4_OS= Hibernate).
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