Datasheet

Thermal Management
Intel
®
Xeon
®
and Intel
®
Core™ Processors For Communications Infrastructure
May 2012 Datasheet - Volume 1 of 2
Document Number: 327405
-001 63
7.3 Thermal Management Features
This section covers thermal management features for the processor.
7.3.1 Processor Package Thermal Features
This section covers thermal management features for the entire processor complex
(including the processor core and integrated memory controller hub) and is referred to
as processor package or package.
Occasionally the package operates in conditions that exceed its maximum allowable
operating temperature. This can be due to internal overheating or due to overheating in
the entire system. In order to protect itself and the system from thermal failure, the
package is capable of reducing its power consumption and thereby its temperature to
attempt to remain within normal operating limits via the Adaptive Thermal Monitor.
The Adaptive Thermal Monitor can be activated when any package temperature,
monitored by a digital thermal sensor (DTS), meets or exceeds its maximum junction
temperature specification (T
J-MAX
) and asserts PROCHOT#. The thermal control circuit
(TCC) can be activated prior to T
J-MAX
by use of the TCC activation offset. The assertion
of PROCHOT# activates the Thermal Control Circuit (TCC), and causes the processor
core to reduce frequency and voltage adaptively. The TCC remains active as long as
any package temperature exceeds its specified limit. Therefore, the Adaptive Thermal
Monitor continues to reduce the package frequency and voltage until the TCC is de-
activated. If properly configured, when an external device asserts PROCHOT# the
thermal control circuit (TCC) causes the processor core to reduce frequency and
voltage adaptively.
Note: Adaptive Thermal Monitor is always enabled.
7.3.1.1 Adaptive Thermal Monitor
The purpose of the Adaptive Thermal Monitor is to reduce processor core power
consumption and temperature until it operates at or below its maximum operating
temperature (according for TCC activation offset). Processor core power reduction is
achieved by:
• Adjusting the operating frequency (via the core ratio multiplier) and input voltage
(via the SVID bus).
• Modulating (starting and stopping) the internal processor core clocks (duty cycle).
The temperature at which the Adaptive Thermal Monitor activates the Thermal Control
Circuit is factory calibrated and is not user configurable. The default value is software
visible in the TEMPERATURE_TARGET (0x1A2) MSR, Bits 23:16. The Adaptive Thermal
Monitor does not require any additional hardware, software drivers, or interrupt
handling routines.
Note: The Adaptive Thermal Monitor is not intended as a mechanism to maintain processor
TDP. The system design should provide a thermal solution that can maintain TDP within
its intended usage range.
7.3.1.1.1 Frequency/Voltage Control
Upon TCC activation, the processor core attempts to dynamically reduce processor core
power by lowering the frequency and voltage operating point. The operating points are
automatically calculated by the processor core itself and do not require the BIOS to
program them as with previous generations of Intel processors. The processor core
scales the operating points so that: