Intel Pentium 4 641 HH80552PG0882M Manuale Utente
Codici prodotto
HH80552PG0882M
Datasheet
79
Thermal Specifications and Design Considerations
The PROCHOT# signal is asserted when a high temperature situation is detected, regardless of
whether or not Thermal Monitor or Thermal Monitor 2 is enabled.
whether or not Thermal Monitor or Thermal Monitor 2 is enabled.
It should be noted that the Thermal Monitor 2 TCC can not be activated via the on demand mode.
The Thermal Monitor TCC, however, can be activated through the use of the on demand mode.
The Thermal Monitor TCC, however, can be activated through the use of the on demand mode.
5.2.3
On-Demand Mode
The Pentium 4 processor in the 775-land package 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
Pentium 4 processor in the 775-land package must not rely on software usage of this mechanism to
limit the processor temperature.
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
Pentium 4 processor in the 775-land package 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.
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.
5.2.4
PROCHOT# Signal
An external signal, PROCHOT# (processor hot), is asserted when the processor die temperature
has reached its maximum operating temperature. If the Thermal Monitor is enabled (note that the
Thermal Monitor must be enabled for the processor to be operating within specification), the TCC
has reached its maximum operating temperature. If the Thermal Monitor is enabled (note that the
Thermal Monitor must be enabled for the processor to be operating within specification), the TCC
Figure 5-4. Thermal Monitor 2 Frequency and Voltage Ordering
VID
Frequency
Temperature
T
TM2
f
MAX
f
TM2
VID
VID
TM2
PROCHOT#
Time