Chapter 2 | Specifications |
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(Tn-Tn-1) + TC2(Tn-Tt)
ΔP is the performance delta
Tt is the target temperature = critical trip point.
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 | Conditions/Remarks |
Power Button | Wakes unconditionally from |
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GPI1# | 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. |
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22 | Reference Manual | COM 830 |