Thermal Specifications
Figure 7-3. Thermal Monitor 2 Frequency and Voltage Ordering
T
TM2
Temperature
Frequency
f
f
MAX
TM2
V
V
NOM
TM2
Vcc
Time
T(hysteresis)
The PROCHOT# signal is asserted when a high temperature situation is detected, regardless of
whether Thermal Monitor or Thermal Monitor 2 is enabled.
If a processor has its Thermal Control Circuit activated via a Thermal Monitor 2 event, and an
“
Enhanced Intel SpeedStep technology transition to a higher target frequency (through the
applicable MSR write) is attempted, this frequency transition will be delayed until the TCC is
deactivated and the TM2 event is complete.
7.2.3
On-Demand Mode
The 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 and Thermal Monitor 2 features. On-Demand mode is intended
as a means to reduce system level power consumption. Systems must not rely on software usage of
this mechanism to limit the processor temperature.
If bit 4 of the IA_32_CLOCK_MODULATION 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
IA_32_CLOCK_MODULATION MSR. 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 or Thermal Monitor 2. If Thermal Monitor is
enabled and 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.
102
64-bit Intel® Xeon™ Processor MP with up to 8MB L3 Cache Datasheet
INTEL [ INTEL ]
