Intel III Xeon 667 MHz 80526KZ667256 Data Sheet
Product codes
80526KZ667256
PENTIUM® III XEON™ PROCESSOR AT 600 MHz to 1 GHz with 256KB L2 Cache
BOXED PROCESSOR SPECIFICATIONS
85
9.3 Thermal Specifications
This section describes the cooling requirements of the heat sink solution utilized by the boxed processor.
9.3.1 Boxed Processor Cooling Requirements
The boxed processor passive heat sink requires airflow horizontally across the heat sink to cool the processor.
The boxed processor heat sink will keep the processor thermal plate temperature, T
The boxed processor heat sink will keep the processor thermal plate temperature, T
PLATE
, within the
specification, provided adequate airflow is directed into the system chassis, across the heat sink and out of
the system chassis. System integrators should perform thermal testing using thermocouples (see the section
entitled Processor Thermal Analysis) to evaluate the thermal efficiency of the system.
the system chassis. System integrators should perform thermal testing using thermocouples (see the section
entitled Processor Thermal Analysis) to evaluate the thermal efficiency of the system.
9.3.2 Boxed Processor Passive Heat sink Performance
The boxed processor’s passive heat sink is designed to provide effective heat transfer between the processor
package thermal plate and the air immediately surrounding the heat sink. The direction and temperature of air
flowing across the heat sink variably affects the efficiency of the heat sink. Figure 36 shows the thermal
efficiency of the boxed processor heat sink, using three different directions of airflow: horizontal, top-down,
and normal to the plane of the thermal plate. The performance characterization was completed in a wind
tunnel, using a processor running at maximum power and at maximum thermal specification. The
characterization assumes that air entering the heat sink is at constant temperature and uniformly traverses the
heat sink, and that heated air is evacuated from the chassis and is not re-circulated. The characterization also
assumes natural obstructions, such as the motherboard in a top-down airflow model.
package thermal plate and the air immediately surrounding the heat sink. The direction and temperature of air
flowing across the heat sink variably affects the efficiency of the heat sink. Figure 36 shows the thermal
efficiency of the boxed processor heat sink, using three different directions of airflow: horizontal, top-down,
and normal to the plane of the thermal plate. The performance characterization was completed in a wind
tunnel, using a processor running at maximum power and at maximum thermal specification. The
characterization assumes that air entering the heat sink is at constant temperature and uniformly traverses the
heat sink, and that heated air is evacuated from the chassis and is not re-circulated. The characterization also
assumes natural obstructions, such as the motherboard in a top-down airflow model.
To determine if a particular chassis has appropriate airflow to effectively cool the processor, measure the
“upstream” temperature (T
“upstream” temperature (T
AMBIENT
, the ambient air temperature within the chassis) and the velocity of the air
entering the heat sink. The Y-axis in Figure 36 represents the thermal resistance (
θ
PA
) and the X-axis
represents the airflow speed in linear feet per minute (lfm).
θ
PA
can be calculated as the difference between
the thermal plate temperature and ambient air temperature (within the chassis) divided by the processor’s
maximum power specification.
maximum power specification.
θ
PA
=
T
PLATE
- T
AMBIENT
P
MAX
To determine if your airflow is adequate, determine the airflow speed and direction, and identify the
appropriate curve in Figure 36. Calculate
appropriate curve in Figure 36. Calculate
θ
PA
and determine if it falls below the graphed line at the appropriate
airflow speed
Figure 36. Boxed Processor Heat sink Performance
Figure 36 also shows the performance of the boxed processor heat sink with an attached auxiliary fan (50mm
X 50mm X 15mm). In this case, the temperature of the air entering the fan is used as T
X 50mm X 15mm). In this case, the temperature of the air entering the fan is used as T
AMBIENT
. T
AMBIENT
is
measured just outside the fan’s air intake. The presence of the auxiliary fan allows the cooling solution to
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
100
150
200
250
300
350
400
Airflow Speed (lfm)
PA
Horizontal
Normal
Top-Down
Aux. Fan (50mm)