Data Sheet

Datasheet, Volume 1 of 2 97
Thermal Management
interrupt, if enabled. For more details on the interrupt mechanism, refer to the Intel
®
64 and IA-32 Architectures Software Developer’s Manual or appropriate processor
family BIOS Specification (Refer Related Documents section).
5.1.5.10 On-Demand Mode
The processor provides an auxiliary mechanism that allows system software to force
the processor to reduce its power consumption using clock modulation. This
mechanism is referred to as “On-Demand” mode and is distinct from Adaptive Thermal
Monitor and bi-directional PROCHOT#. The processor platforms should not rely on
software usage of this mechanism to limit the processor temperature. On-Demand
Mode can be accomplished using processor MSR or chipset I/O emulation. On-Demand
Mode may be used in conjunction with the Adaptive Thermal Monitor. However, if the
system software 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. If the I/O based and MSR-based On-Demand modes
are in conflict, the duty cycle selected by the I/O emulation-based On-Demand mode
will take precedence over the MSR-based On-Demand Mode.
5.1.5.11 MSR Based On-Demand Mode
If Bit 4 of the IA32_CLOCK_MODULATION MSR is set to 1, the processor will
immediately reduce its power consumption using modulation of the internal processor
IA core clock, independent of the processor temperature. The duty cycle of the clock
modulation is programmable using bits [3:1] of the same IA32_CLOCK_MODULATION
MSR. In this mode, the duty cycle can be programmed in either 12.5% or 6.25%
increments (discoverable using CPUID). Thermal throttling using this method will
modulate each processor IA core's clock independently.
5.1.5.12 I/O Emulation-Based On-Demand Mode
I/O emulation-based clock modulation provides legacy support for operating system
software that initiates clock modulation through I/O writes to ACPI defined processor
clock control registers on the chipset (PROC_CNT). Thermal throttling using this
method will modulate all processor IA cores simultaneously.
5.1.6 Intel
®
Memory Thermal Management
The processor provides thermal protection for system memory by throttling memory
traffic when using either DIMM modules or a memory down implementation. Two levels
of throttling are supported by the processor, either a warm threshold or hot threshold
that is customizable through memory mapped I/O registers. Throttling based on the
warm threshold should be an intermediate level of throttling. Throttling based on the
hot threshold should be the most severe. The amount of throttling is dynamically
controlled by the processor.
The on Die Thermal Sensor (ODTS) uses a physical thermal sensor on DRAM dies.
ODTS is available for DDR4 and LPDDR3. It is used to set refresh rate according to
DRAM temperature.
The memory controller reads LPDDR3 MR4 or DDR4 MR3 and configures the DDR
refresh rate accordingly.