Intel Pentium 4 Processor on 90 nm Process Thermal and Mechanical Design Guidelines

Introduction
R
10 Intel
®
Pentium
®
4 on 90 nm Process Thermal Design Guide
1.1 Overview
As the complexities of today’s microprocessors increase, the power dissipation requirements
become more exacting. Care must be taken to ensure that the additional power is properly
dissipated. Heat can be dissipated using passive heatsinks, fans, and/or active cooling devices.
Incorporating ducted airflow solutions into the system thermal design can yield additional margin.
The Pentium 4 processor on 90 nm process integrates thermal management logic onto the
processor silicon. The Thermal Monitor feature is automatically configured to control the
processor temperature. In the event the die temperature reaches a factory-calibrated temperature,
the processor will take steps to reduce power consumption, causing the processor to cool down
and stay within thermal specifications. Various registers and bus signals are available to monitor
and control the processor thermal status. A thermal solution designed to the TDP and case
temperature, T
C
, as specified in the Intel
®
Pentium
®
4 Processor on 90 nm Process Datasheet, can
adequately cool the processor to a level where activation of the Thermal Monitor feature is either
very rare or non-existent. Various levels of performance versus cooling capacity are available and
must be understood before designing a chassis. Automatic thermal management must be used as
part of the total system thermal solution.
The size and type of the heatsink, as well as the output of the fan can be varied to balance size,
cost, and space constraints with acoustic noise. This document presents the conditions and
requirements for designing a heatsink solution for a system based on a Pentium 4 processor on 90
nm process. Properly designed solutions provide adequate cooling to maintain the processor
thermal specification. This is accomplished by providing a low local ambient temperature and
creating a minimal thermal resistance to that local ambient temperature. Fan heatsinks or ducting
can be used to cool the processor if proper package temperatures cannot be maintained otherwise.
By maintaining the processor case temperature at the values specified in the processor datasheet, a
system designer can be confident of proper functionality and reliability of these processors.