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Chapter 2
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 according to the formula below.
ΔP[%] = TC1(T
ΔP is the performance delta
T
is the target temperature = critical trip point.
t
The two coefficients TC1 and TC2 and the sampling period TSP are hardware
dependent constants. These constants are set to fixed values for the COM 830:
TC1= 1
TC2= 5
TSP= 5 seconds
See section 12 of the ACPI Specification 2.0 C for more information about passive
cooling.
ACPI Suspend Modes and Resume Events
COM 830 supports the S1 (POS= Power On Suspend) state and S3 (STR= Suspend to RAM). For more
information about S3 wake events see section "ACPI Configuration Submenu".
S4 (Suspend to Disk) is not supported by the BIOS (S4_BIOS) but it is supported by the following operating
systems (S4_OS= Hibernate):
Win2K
WinXP
The following table lists the "Wake Events" that resume the system from both S1 or S3 unless otherwise
stated in the "Conditions/Remarks" column:
Wake Event
Power Button
GPI1#
22
-T
) + TC2(T
-T
)
n
n-1
n
t
Conditions/Remarks
Wakes unconditionally from S1-S5.
Only if configured as Lid Switch in the ACPI setup menu. Additionally the
lid button has to be activated using the Windows Power Options. The best
way to use it is to go to Standby (see note below) on lid button press and
wake from Standby (see note below) on lid button release.
Reference Manual
Specifications
COM 830
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