Datasheet 85
Thermal Specifications and Design Considerations
EMTTM is a processor feature that enhances Intel Thermal Monitor 2 with a processor
throttling algorithm known as Adaptiv e Intel Thermal Monitor 2. Adaptive Intel Thermal
Monitor 2 transitions to intermediate operating points, rather than directly to the LFM,
once the processor has reached its thermal limit and subsequently searches for the
highest possible operating point. Please ensure this feature is enabled and supported in
the BIOS. Also with EMT TM enabled, the operating system can request the processor to
throttling to any point between Intel Dynamic Acceleration Technology frequency and
SuperLFM frequency as long as these features are enabled in the BIOS and supported
by the processor. The Intel Thermal Monitor automatic mode and Enhanced Multi
Threaded Thermal Monitoring must be enabled through BIOS for the processor to be
operating within specifications.
Note: Intel Thermal Monitor 1, Intel Thermal Monitor 2 and EMTTM features are collectively
referred to as Adaptive Thermal Monitoring features. Intel recommends Intel Thermal
Monitor 1 and 2 be enabled on the processors.
Intel Thermal Monitor 1 and 2 can co-exist within the processor. If both Intel Thermal
Monitor 1 and 2 bits are enabled in the auto-throttle MSR, Intel Thermal Monitor 2
takes precedence over Intel Thermal Monitor 1. However, if Force Intel Thermal Monitor
1 over Intel Thermal Monitor 2 is enabled in MSRs via BIOS and Intel Thermal Monitor
2 is not sufficient to cool the processor below the maximum operating temperature,
then Intel Thermal Monitor 1 also activates to help cool down the processor.
If a processor load based Enhanced Intel SpeedStep Technology transition (through
MSR write) is initiated when a Intel Thermal Monitor 2 period is active, there are two
possible results:
1. If the processor load based Enhanced Intel SpeedStep Technology transition target
frequency is higher than the Intel Thermal Monitor 2 transition-based target
frequency, the processor load-based transition deferrs until the Intel Thermal
Monitor 2 event has been completed.
2. If the processor load-based Enhanced Intel SpeedStep Technology transition target
frequency is lower than the Intel Thermal Monitor 2 transition-based target
frequency, the processor transitions to the processor load-based Enhanced Intel
SpeedStep Technology target frequency point.
The TCC may also be activ ated via on-demand mode. If bit 4 of the ACPI Intel Thermal
Monitor control register is written to a 1, the TCC activates immediately independent of
the processor temper ature. When using on-demand mode to activate the T CC, the duty
cycle of the clock modulation is programmable via bits 3:1 of the same ACPI Intel
Thermal Monitor control register. In automatic mode, the duty cycle is fixed at 50% on,
50% off, however in on-demand mode, the dut y cycle can be progr ammed from 12.5%
on/ 87.5% off , to 87.5% on/12.5% off in 12.5% increments. On-demand mode may be
used at the same time automatic mode is enabled, however, if the system tries to
enable the TCC via on-demand mode at the same time automatic mode is enabled and
a high temperature condition exists, automatic mode takes precedence.
An external signal, PROCHOT# (processor hot) is asserted when the processor detects
that its temperature is above the thermal trip point. Bus snooping and interrupt
latching are also active while the TCC is active.
Besides the thermal sensor and thermal control circuit, the Intel Thermal Monitor also
includes one ACPI register, one performance counter register, three MSR, and one I/O
pin (PROCHOT #). All are available to monitor and control the state of the Intel Thermal
Monitor feature. The Intel Thermal Monitor can be configured to generate an interrupt
upon the assertion or deassertion of PROCHOT#.
PROCHOT# is not be asserted when the processor is in the Stop Grant, Sleep, Deep
Sleep, and Deeper Sleep low power states, hence the thermal diode reading must be
used as a safeguard to maintain the processor junction temperature within maximum
specification. If the platform thermal solution is not able to maintain the processor