Table of Contents
Advertisement
6.2
Processor Thermal Features
6.2.1
Processor Temperature
A new feature in the Intel Xeon Processor 3500 Series is a software readable field in the
IA32_TEMPERATURE_TARGET register that contains the minimum temperature at
which the TCC will be activated and PROCHOT# will be asserted. The TCC activation
temperature is calibrated on a part-by-part basis and normal factory variation may
result in the actual TCC activation temperature being higher than the value listed in the
register. TCC activation temperatures may change based on processor stepping,
frequency or manufacturing efficiencies.
Note:
There is no specified correlation between DTS temperatures and processor case
temperatures; therefore it is not possible to use this feature to ensure the processor
case temperature meets the Thermal Profile specifications.
6.2.2
Adaptive Thermal Monitor
The Adaptive Thermal Monitor feature provides an enhanced method for controlling the
processor temperature when the processor silicon exceeds the Thermal Control Circuit
(TCC) activation temperature. Adaptive Thermal Monitor uses TCC activation to reduce
processor power via a combination of methods. The first method (Frequency/VID
control, similar to Thermal Monitor 2 (TM2) in previous generation processors) involves
the processor reducing its operating frequency (via the core ratio multiplier) and input
voltage (via the VID signals). This combination of lower frequency and VID results in a
reduction of the processor power consumption. The second method (clock modulation,
known as Intel® Thermal Monitor 1 (TM1) in previous generation processors) reduces
power consumption by modulating (starting and stopping) the internal processor core
clocks. The processor intelligently selects the appropriate TCC method to use on a
dynamic basis. BIOS is not required to select a specific method (as with previous-
generation processors supporting TM1 or TM2). The temperature at which Adaptive
Thermal Monitor activates the Thermal Control Circuit is factory calibrated and is not
user configurable. Snooping and interrupt processing are performed in the normal
manner while the TCC is active.
When the TCC activation temperature is reached, the processor will initiate TM2 in
attempt to reduce its temperature. If TM2 is unable to reduce the processor
temperature then TM1 will be also be activated. TM1 and TM2 will work together (clocks
will be modulated at the lowest frequency ratio) to reduce power dissipation and
temperature.
With a properly designed and characterized thermal solution, it is anticipated that the
TCC would only be activated for very short periods of time when running the most
power intensive applications. The processor performance impact due to these brief
periods of TCC activation is expected to be so minor that it would be immeasurable. An
under-designed thermal solution that is not able to prevent excessive activation of the
TCC in the anticipated ambient environment may cause a noticeable performance loss,
and in some cases may result in a T
temperature and may affect the long-term reliability of the processor. In addition, a
thermal solution that is significantly under-designed may not be capable of cooling the
processor even when the TCC is active continuously. Refer to the appropriate processor
Thermal and Mechanical Design Guide (see
compliant thermal solution.
84
that exceeds the specified maximum
CASE
Section
1.2) for information on designing a
Intel® Xeon® Processor 3500 Series Datasheet Volume 1
Thermal Specifications
Advertisement
Table of Contents
