Quad-Core Intel® Xeon® Processor 5400 Series TMDG 33
Thermal/Mechanical Reference Design
2.4 Characterizing Cooling Solution Performance
Requirements
2.4.1 Fan Speed Control
Fan speed control (FSC) techniques to reduce system level acoustic noise are a
common practice in server designs. The fan speed is one of the parameters that
determine the amount of airflow provided to the thermal solution. Additionally, airflow
is proportional to a thermal solution’s performance, which consequently determines the
T
CASE
of the processor at a given power level. Since the T
CASE
of a processor is an
important parameter in the long-term reliability of a processor, the FSC implemented in
a system directly correlates to the processor’s ability to meet the Thermal Profile and
hence the long-term reliability requirements. For this purpose, the parameter called
T
CONTROL
as explained in Section 2.2.6, 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. Figure 2-14 depicts the relationship between T
CONTROL
and FSC
methodology.
Once the T
CONTROL
value is determined as explained earlier, the DTS temperature
reading from the processor can be compared to this T
CONTROL
value. A fan speed
control scheme can be implemented as described in Tabl e 2- 6 without compromising
the long-term reliability of the processor.
Figure 2-14. T
CONTROL
and Fan Speed Control
