Intel Celeron 360 HH80552RE099512 User Manual

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periods of TCC activation is expected to be so minor that it would be immeasurable. An 

under-designed thermal solution that is not able to prevent excessive activation of the 

TCC in the anticipated ambient environment may cause a noticeable performance loss, 

and in some cases may result in a T

C

 that exceeds the specified maximum temperature 

and may affect the long-term reliability of the processor. In addition, a thermal solution 

that is significantly under-designed may not be capable of cooling the processor even 

when the TCC is active continuously. Refer to the appropriate processor Thermal and 

Mechanical Design Guidelines (see 

) for information on designing a thermal 

solution.

The duty cycle for the TCC, when activated by the Thermal Monitor, is factory 

configured and cannot be modified. The Thermal Monitor does not require any 

additional hardware, software drivers, or interrupt handling routines.

The Celeron D processor provides an auxiliary mechanism that allows system software 

to force the processor to reduce its power consumption. This mechanism is referred to 

as “On-Demand” mode and is distinct from the Thermal Monitor feature. On-Demand 

mode is intended as a means to reduce system level power consumption. Systems 

using the Celeron D processor must not rely on software usage of this mechanism to 

limit the processor temperature.

If bit 4 of the ACPI P_CNT Control Register (located in the processor 

IA32_THERM_CONTROL MSR) is written to a '1', the processor will immediately reduce 

its power consumption via modulation (starting and stopping) of the internal core clock, 

independent of the processor temperature. When using On-Demand mode, the duty 

cycle of the clock modulation is programmable via bits 3:1 of the same ACPI P_CNT 

Control Register. In On-Demand mode, the duty cycle can be programmed from 12.5% 

on/87.5% off, to 87.5% on/12.5% off in 12.5% increments. On-Demand mode may be 

used in conjunction with the Thermal Monitor. If the system tries to enable On-Demand 

mode at the same time the TCC is engaged, the factory configured duty cycle of the 

TCC will override the duty cycle selected by the On-Demand mode.