User Guide

Thermal Management
90 Datasheet, Volume 1 of 2
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.
Memory temperature can be acquired through an on-board thermal sensor (TS-on-
Board), retrieved by an embedded controller and reports to the processor through the
PECI 3.1 interface. This methodology is known as PECI injected temperatures. This is a
method of Closed Loop Thermal Management (CLTM). CLTM requires the use of a
physical thermal sensor. EXTTS# is another method of CLTM but it is only capable of
reporting memory thermal status to the processor. EXTTS# consists of two GPIO pins
on the PCH, where the state of the pins is communicated internally to the processor.
When a physical thermal sensor is not available to report temperature, the processor
supports Open Loop Thermal Management (OLTM) that estimates the power consumed
per rank of the memory using the processor's DRAM power meter. A per rank power is
associated with the warm and hot thresholds that, when exceeded, may trigger
memory thermal throttling.
5.1.7 Scenario Design Power (SDP)
SDP requires that the POWER_LIMIT_1 (PL1) to be set to the cooling level capability
(SDP level, or higher). While the SDP specification is characterized at Tj of 80 °C, the
functional limit for the product remains at Tj
MAX
. Customers may choose to program
the TCC Offset to have TCC Activation at 80 °C, but it is not required.
The processors that have SDP specified can still exceed SDP under certain workloads,
such as TDP workloads. TDP power dissipation is still possible with the intended usage
models, and protection mechanisms to handle levels beyond cooling capabilities are
recommended. Intel recommends using such thermal control mechanisms to manage
situations where power may exceed the thermal design capability.
Note: cTDP-Down mode is required for Intel Core products in order to achieve SDP.
Note: Although SDP is defined at 80 °C, the TCC activation temperature is Tj
MAX
.