• Introduction
• Thermal Management
• Fan Heatsink 
• Chassis Recommendations
• Pentium® III Processor Thermal Specifications
• Fahrenheit to Celsius Conversion Chart 

Introduction
Systems using Intel® Pentium® III processors all require thermal management. The reader should have a general knowledge of and experience with PC operation, integration, and thermal management. Integrators who follow the recommendations presented can provide their customers with more reliable PCs and will see fewer customers returning with thermal management issues. (The term "boxed Pentium® III processors" refers to processors packaged for use by system integrators.)

Allowing processors to operate at temperatures beyond their maximum specified operating temperature may shorten the life of the processor and can cause unreliable operation. When building quality systems using the boxed Pentium III processor, it is imperative that you carefully consider the thermal management of the system and verify the system design with thermal testing. This document details specific thermal requirements of the boxed Pentium III processor. System integrators using the boxed Pentium® III processor should become familiar with this document as well as the two related documents listed below 

Thermal Management
The term "thermal management" refers to two major elements: a heatsink properly mounted to the processor, and effective airflow through the system chassis. The ultimate goal of thermal management is to keep the processor at or below its maximum operating temperature.

Proper thermal management is achieved when heat is transferred from the processor to the system air, which is then vented out of the system. Boxed Pentium® III processors are shipped with a high-quality fan heatsink, which can effectively transfer processor heat to the system air. It is the responsibility of the system integrator to ensure adequate system airflow. 

Fan Heatsink
The fan heatsink included with the boxed Pentium® III processor must be securely attached to the processor. Thermal interface material (already applied) provides effective heat transfer from the processor to the fan heatsink. The fan cable provides power to the fan by connecting to a motherboard-mounted power header and also allows the fan to provide fan speed information to the motherboard. (Only motherboards with hardware monitoring circuitry can use the fan speed signal.)

The fan is a high-quality ball bearing fan that provides a good local air stream. This air stream transfers heat from the heatsink to the air inside the system. However, moving heat to the system air is only half the task. Sufficient system airflow is also needed in order to exhaust the air. Without a steady stream of air through the system, the fan heatsink will re-circulate warm air, and therefore may not cool the processor adequately. 

Chassis Recommendations
Intel recommends the use of ATX and microATX form factor boards and chassis for the boxed Pentium® III processor. The ATX and microATX form factors provide consistency of airflow to the processor and simplify PC assembly and upgrade.

Pentium® III Processor Thermal Specifications
Table 1 lists the power dissipation of boxed Pentium® III processors. Use the thermal test methodology described in "Thermal Testing with Thermocouples and Thermal Meters on Intel Boxed Processor-Based Desktop PCs" to test thermal management of boxed Pentium III processor-based systems. When building 242-contact slot connector systems that will feature boxed Pentium III processors, testing should be performed using the 600-MHz or a 600B-MHz processor because it dissipates the most power. When building 370-pin socket systems that will feature boxed Pentium III processors, testing should be performed using the 800-MHz or 800EB-MHz processor because it dissipates the most power. 

Table 1 lists the boxed Pentium® III processor temperature specifications. 

Table 1. Boxed Pentium® III Processor Thermal Specifications¹

Processor Frequency	Form Factor	Temperatures			Total Max Processor Power
		Max Core (TJ)2	Recommended Fan Inlet (TA)3	Recommended Heatsink Base (THS)4
933 MHz	S.E.C.C.2	75°C	45°C	N/A5	25.5 W
933 MHz	FC-PGA	75°C	45°C	N/A5	24.5 W
866 MHz	S.E.C.C.2	80°C	45°C	N/A5	22.9 W
866 MHz	FC-PGA	80°C	45°C	N/A5	22.9 W
850 MHz	S.E.C.C.2	80°C	45°C	N/A5	22.5 W
850 MHz	FC-PGA	80°C	45°C	N/A5	22.5 W
800EB MHz	S.E.C.C.2	80°C	45°C	N/A5	20.8 W
800EB MHz	FC-PGA	80°C	45°C	N/A5	20.8 W
800 MHz	S.E.C.C.2	80°C	45°C	N/A5	20.8 W
800 MHz	FC-PGA	80°C	45°C	N/A5	20.8 W
750 MHz	S.E.C.C.2	80°C	45°C	N/A5	19.5 W
750 MHz	FC-PGA	80°C	45°C	N/A5	19.5 W
733 MHz	S.E.C.C.2	80°C	47°C	N/A5	19.1 W
733 MHz	FC-PGA	80°C	47°C	N/A5	19.1 W
700 MHz	S.E.C.C.2	80°C	47°C	N/A5	18.3 W
700 MHz	FC-PGA	80°C	47°C	N/A5	18.3 W
667 MHz	S.E.C.C.2	82°C	50°C	N/A5	17.5 W
667 MHz	FC-PGA	82°C	50°C	N/A5	17.5 W
650 MHz	S.E.C.C.2	82°C	53°C	N/A5	17.0 W
650 MHz	FC-PGA	82°C	53°C	N/A5	17.0 W
600EB MHz	S.E.C.C.2	82°C	48°C	N/A5	15.8 W
600EB MHz	FC-PGA	82°C	48°C	N/A5	15.8 W
600E MHz	S.E.C.C.2	82°C	48°C	N/A5	15.8 W
600E MHz	FC-PGA	82°C	48°C	N/A5	15.8 W
600B MHz	S.E.C.C.2	85°C	45°C	60°C	34.5 W
600 MHz	S.E.C.C.2	85°C	45°C	60°C	34.5 W
550E MHz	S.E.C.C.2	85°C	50°C	N/A5	14.5 W
550E MHz	FC-PGA	85°C	50°C	N/A5	14.5 W
550 MHz	S.E.C.C.2	80°C	45°C	60°C	30.8 W
533EB MHz	S.E.C.C.2	82°C	50°C	N/A5	14.0 W
533EB MHz	FC-PGA	82°C	50°C	N/A5	14.0 W
533B MHz	S.E.C.C.2	90°C	47°C	61°C	29.7 W
500E MHz	FC-PGA	85°C	53°C	N/A5	13.2 W
500 MHz	S.E.C.C.2	90°C	50°C	62°C	28.0 W
450 MHz	S.E.C.C.2	90°C	53°C	65°C	25.3 W

A simple evaluation of the temperature of the heatsink base can provide confidence in the system's thermal management. For boxed Pentium® III processors in the S.E.C.C.2 form factor, the testing point is at the center of the heatsink base on the top of the processor near to the processor marking area (see Figure 1). The document "Thermal Testing with Thermocouples and Thermal Meters on Intel Boxed Processor-Based PCs" describes how to determine the temperature of this location while running a high power application. Evaluation of test data makes it possible to determine if a system has sufficient thermal management for the boxed processor. A more general evaluation can be performed by testing the temperature of air entering the fan inlet. Table 1 lists the recommended temperature that the heatsink base test point or the air inlet temperature should remain below during the thermal evaluation of a system.

Figure 1. S.E.C.C.2 Boxed Pentium® III Processor
Temperature Test Locations

For boxed Pentium® III processors in the FC-PGA package, the testing point is 0.3 inches above the center of the fan inlet. (see Figure 2).

Figure 2. FC-PGA Boxed Pentium® III Processor
Temperature Test Locations

Fahrenheit to Celsius Conversion Chart