Thermal Specifications and Design Guidelines
Intel
®
Xeon
®
Phi™ Processor x200 Product Family TMSDG
Order Number: 334785-002
46
The processor and MCDRAM power varies dramatically by workload and they do not
achieve their maximum allowable values concurrently. Thus, a processor-centric
workload maximizes processor power while typically drawing lower MCDRAM power.
Conversely, a memory centric workload maximizes MCDRAM power while requiring
concurrently a processor power lower than that of the processor centric workload. This
is very important to consider when analyzing, designing and testing T
CASE
thermal
solutions.
A couple of processor with fabric examples are provided to illustrate these
relationships, with values representing the Intel reference thermal solution:
Example 1: Processor T
CASE
based on a hypothetical processor centric type workload.
T
CASE_CPU
= T
LA
+
CC
* P
CPU
+
CM
* P
MCDRAM
+
CF
* P
Fabric
= 40 + (0.212) * (185) + (0.134) * (30) + (0.140) * (15) = 85
°
C
Example 2: MCDRAM T
CASE
based on a hypothetical memory centric type workload.
T
CASE_MCDRAM
= T
LA
+
MC
* P
CPU
+
MM
* P
MCDRAM
+
MF
* P
Fabric
= 40 + (0.147) * (147) + (0.177) * (68) + (0.196) * (15) = 75
°
C
Figure 6-2. Processor with Fabric T
CASE
Measurement Locations.
Notice, the processor with fabric is not symmetric with respect to the airflow direction.
In the previous figure the Fabric die is downstream from the processor and MCDRAM
die and thus preheated by the air flowing across these die. The orientation of the
package impacts the processor thermal performance.
Finally, it is well known that thermal resistance has a strong dependence on system
thermal design parameters such as volumetric airflow. The reference design thermal
resistivity dependence on volumetric airflow is illustrated in
