Thermal Management
68
Datasheet
controller will shut off its internal clocks (thus halting program execution) in an attempt
to reduce the core junction temperature. Once activated, THERMTRIP# remains latched
until RSTIN# is asserted.
5.2.2.5
Render Thermal Throttling
Render Thermal Throttling of the integrated graphics and memory controller allows for
the reduction the render core engine frequency and voltage, thus reducing internal
graphics controller power and integrated graphics and memory controller thermals.
Performance is degraded, but the platform thermal burden is relieved.
Render Thermal Throttling using several frequency/voltage operating points that can be
used to throttle the render core. If the temperature of the integrated graphics and
memory controller internal DTS exceeds the Hot-trip point, the integrated graphics will
switch to a lower frequency/voltage operating point. After a timeout, the DTS is
rechecked, and if the DTS temperature is still greater than the designed hysteresis, the
integrated graphics will continue to switch to lower frequency/voltage operating points.
Once the DTS reports a temperature below the hysteresis value, the render clock
frequency and voltage will be restored to its pre-thermal event state.
Caution:
The Render Thermal Throttling must be enabled for the product to remain within
specification.
5.2.3
Platform Environment Control Interface (PECI)
The Platform Environment Control Interface (PECI) is a one-wire interface that provides
a communication channel between Intel processor and chipset components to external
monitoring devices. The processor implements a PECI interface to allow communication
of processor thermal information to other devices on the platform. The processor
provides a digital thermal sensor (DTS) for fan speed control. The DTS is calibrated at
the factory to provide a digital representation of relative processor temperature.
Averaged DTS values are read via the PECI interface.
The PECI physical layer is a self-clocked one-wire bus that begins each bit with a
driven, rising edge from an idle level near zero volts. The duration of the signal driven
high depends on whether the bit value is a Logic 0 or Logic 1. PECI also includes
variable data transfer rate established with every message. The single wire interface
provides low board routing overhead for the multiple load connections in the congested
routing area near the processor and chipset components. Bus speed, error checking,
and low protocol overhead provides adequate link bandwidth and reliability to transfer
critical device operating conditions and configuration information.
5.2.3.1
Fan Speed Control with Digital Thermal Sensor
Digital Thermal Sensor based fan speed control (T
FAN
) is a recommended feature to
achieve optimal thermal performance. At the T
FAN
temperature, Intel recommends full
cooling capability well before the DTS reading reaches T
j,max
. An example of this would
be T
FAN
= T
j,max
- 10ºC.
