Thermal Specifications and Design Guidelines
Intel
®
Xeon
®
Phi™ Processor x200 Product Family TMSDG
Order Number: 334785-002
52
in a system directly correlates to the processor’s ability to meet thermal targets. For
this purpose, the parameter called T
CONTROL,
is to be used in FSC designs to ensure
that the long-term reliability of the processor is met while keeping the system-level
acoustic noise down.
When DTS values are less than T
CONTROL,
the thermal target can be ignored. The DTS
value is a relative temperature to PROCHOT which is the maximum allowable
temperature before the thermal control circuit is activated. In this region, the DTS
value can be utilized to not only ensure specification compliance but also to optimize
FSC resulting in the lowest possible fan power and acoustics under any operating
condition. When DTS goes above T
CONTROL,
fan speed must increase to bring the sensor
temperature below T
CONTROL
or to ensure compliance with the T
CASE
profile.
The PECI temperature reading from the processor can be compared to this T
CONTROL
value. An FSC scheme can be implemented without compromising the long-term
reliability of the processor. The PECI command for DTS is GetTemp(). Through use of a
sign bit, the value returned from PECI is negative. The PECI command for T
CONTROL
is
RdPkgConfig(), Temperature Target Read, 15:8. The value returned from PECI, while
unsigned (positive), is negative by definition.
There are many different ways of implementing FSC; including methods based on
processor ambient temperature, processor DTS, or a combination of the two. If FSC is
based only on the processor ambient temperature, low acoustic targets can be
achieved under low ambient temperature conditions. However, the acoustics cannot be
optimized based on the behavior of the processor temperature. If FSC is based only on
the DTS, sustained temperatures above T
CONTROL
drive fans to maximum RPM. If FSC is
based both on the ambient and DTS, then ambient temperature can be used to scale
the fan RPM controlled by the DTS logic. This would result in an optimal acoustic
performance. Regardless of which scheme is employed, system designers must ensure
the T
CASE
specification is met under all operational conditions.
6.2.4.3
Tcontrol Relief
Intel may choose to provide T
CONTROL
relief near product launch, T
CONTROL
values closer
to 0, as compared to the factory configured T
CONTROL
values. However, there are no
such plans at this time.
6.2.4.4
Thermal Excursion Power
Under fan failure or other anomalous thermal excursions, processor temperature
(either T
CASE
or DTS) may exceed the thermal target for a duration totaling less than
360 hours per year without affecting long term reliability (life) of the processor. For
more typical thermal excursions, the thermal monitor is expected to control the
processor temperature by reducing the processor power level. These conditions should
not allow the processor to exceed the temperature at which the Thermal Control Circuit
(TCC) activation initially occurred.
Under more severe anomalous thermal excursions when the processor temperature
cannot be controlled at or below thermal profile by TCC activation, then data integrity is
not assured. At some higher thresholds, THERMTRIP_N will enable a shut down in an
attempt to prevent permanent damage to the processor.
Thermal test vehicles (TTVs) may be used to check anomalous thermal excursion
compliance. TTVs can be used to test and ensure the processor T
CASE
value does not
exceed T
CASE_MAX
at the anomalous power level for the condition of interest, such as
fan failure.
