D R A F T — F O R I N
T E R N A L U S E O N L Y
61
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User Guide
CP3004-SA
5 Thermal Considerations
The thermal characteristic graphs shown in the following sections are intended to serve as guidance
for reconciling the required computing power with the necessary system volumetric airflow over the
ambient temperature. The graphs contain two curves representing upper level working points based on
different levels of average CPU utilization. When operating below the corresponding curve, the CPU
runs without any intervention of thermal supervision (Intel® Core™ i7-5700EQ is below 105°C; Intel®
Core™ i5-4410E and Intel® Core™ i3-4112E are below 100°C). When operated above the corresponding
curve, various thermal protection mechanisms may take effect resulting in temporarily reduced CPU
performance or finally in an emergency stop (the CPU is at 130°C) in order to protect the CPU from ther-
mal destruction (in this case the power must be switched off and then on again). In real applications
this means that the board can be operated temporarily at a higher ambient temperature or at a reduced
flow rate and still provide some margin for temporarily requested peak performance before thermal
protection will be activated.
An airflow of 2.0 m/s to 3.0 m/s or a volumetric flow rate of 15 CFM to 20 CFM is a typical value for a
standard Kontron ASM rack. For other racks or housings the available airflow will differ. The maximum
ambient operating temperature must be determined for such environments.
How to read the diagram in Figures 7 and 9
Select a specific CPU and choose a specific working point. For a given flow rate there is a maximum air-
flow input temperature (= ambient temperature) provided. Below this operating point, thermal super-
vision will not be activated. Above this operating point, thermal supervision will become active
protecting the CPU from thermal destruction. The minimum airflow rate provided must be more than
the value specified in the diagram.
How to read the diagram in Figure 8
Select a specific working point. For a given CPU frequency there is a maximum airflow input tempera-
ture (= ambient temperature) provided. Below this operating point, thermal supervision will not be ac-
tivated. Above this operating point, thermal supervision will become active by reducing the CPU
frequency to protect the CPU from thermal destruction. The minimum airflow rate provided must be
more than the value specified in the diagram.
Volumetric flow rate
The volumetric flow rate refers to an airflow through a fixed cross-sectional area (i.e. slot width x
depth. The volumetric flow rate is specified in m³/h (cubic-meter-per-hour) or cfm (cubic-feet-per-
minute) respectively.
Conversion: 1 cfm = 1.7 m³/h; 1 m³/h = 0.59 cfm
Airflow
At a given cross-sectional area and a required flow rate, an average, homogeneous airflow speed can
be calculated using the following formula:
Airflow = Volumetric flow rate / area.
