This article was previously published under Q189091
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Windows 98 does not provide support for Passive Cooling Mode as describedin the Advanced Configuration and Power Interface (ACPI) specification.Windows 98 only supports Active Cooling Mode.
The ACPI specification defines two categories of methods for coolingcomputer systems:
Active cooling methods
Passive cooling methods
Active cooling methods may include turning on one or more fans to provideincreased airflow and improve dissipation of heat from active components.these methods cool the computer without decreasing its performance, butincrease power consumption and often increase noise production.
Passive cooling methods may include slowing down (throttling) thecomputer's central processing unit (CPU) so that the CPU generates lessheat. These methods tend to decrease power consumption, but decreaseoverall system performance when used.
A computer which complies with the ACPI specification may operate in oneof two cooling modes:
Active Cooling mode
Passive Cooling mode
In Active Cooling mode, the computer first uses active cooling methods tocontrol the temperature of the computer. If the computer's temperaturecontinues to rise when the active cooling methods are in use, then thecomputer uses passive cooling methods to cool overheated components.
In Passive Cooling mode, the computer first uses passive cooling methodsto control the temperature of the computer. If the computer's temperaturecontinues to rise when the passive cooling methods are in use, then thecomputer uses active cooling methods to cool overheated components.
In either cooling mode, if the temperature continues to rise to criticallevels, the computer may shut down or go to some other non-operating,lower-power state. This is to help prevent thermal damage to components.
The computer's cooling mode is controlled by the temperature set point.This is the temperature at which each cooling method is activated. Forexample, if the set point for the active cooling method is a lowertemperature than the set point for the passive cooling method, then theactive method is employed first, and the computer goes to Active Coolingmode. If the set point for the passive cooling method is lower than theset point for the active cooling method, then the passive method isemployed first, and the computer goes to Passive Cooling mode.
Windows 98 configures the computer to operate only in Active Cooling mode,and does not provide an interface for changing the active and passivecooling set points so that the computer could be reconfigured to operatein Passive Cooling mode.
For more information, please see the following article in the MicrosoftKnowledge Base:
ARTICLE-ID: 189803 TITLE : PRB: PMPI FanThrottleToleranceAc/Dc Not Implemented Under Win98
Information on ACPI specifications and implementation can be found at thefollowing Internet location:
The third-party contact information included in this article is providedto help you find the technical support you need. This contact informationis subject to change without notice. Microsoft in no way guarantees theaccuracy of this third-party contact information.
Active and passive cooling methods and modes are discussed in the ACPIspecification, Revision 1.0, December 22, 1996, in section 12, "ThermalManagement".