Intel 640 User Guide - Page 41

Intel® Thermal/Mechanical Reference Design Information

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Thermal/Mechanical Design Guide

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5.1.4

Reference Heatsink Thermal Validation

The Intel reference heatsink is validated within specific boundary conditions based on the

methodology described in Section 5.2.

Testing is done on bench top test boards at ambient lab temperature. In particular, for the

reference heatsink, the Plexiglas* barrier is installed 81.28 mm [3.2 in] above the motherboard

(refer to Sections 3.3 and 5.6).

The test results, for a number of samples, are reported in terms of a worst-case mean + 3

σ

value

for thermal characterization parameter using actual processors (based on the thermal test vehicle

correction factors).

Note:

The above 81.28 mm obstruction height that is used for testing complies with the recommended

obstruction height of 88.9 mm for the ATX form factor. However, it would not be sufficient for

systems in strict compliance with the ATX specification that defines a 76.2 mm obstruction height

in Area A.

5.1.5

Fan Performance for Active Heatsink Thermal Solution

The fan power requirements for proper operation are given in Table 3.

Table 3. Fan Electrical Performance Requirements

Requirement

Value

Peak fan current draw

1.5 A

Average fan current draw

1.1 A

Fan start-up current draw

2.2 A

Fan start-up current draw maximum

duration

1.0 second

Fan header voltage

12 V ± 10%

Tachometer output

2 pulse per revolution

In addition to comply with overall thermal requirements (Section 5.1.1), and the general

environmental reliability requirements (Section 5.2) the fan should meet the following

performance requirements:

•

Mechanical wear out represents the highest risk reliability parameter for fans. The capability

of the functional mechanical elements (ball bearing, shaft, and tower assembly) must be

demonstrated to a minimum useful lifetime of 50,000 hours.

•

In addition to passing the environmental reliability tests described in Section 5.2, the fan

must demonstrate adequate performance after 7,500 on/off cycles with each cycle specified

as 3 minutes on, 2 minutes off, at a temperature of 70 °C.

See the

Fan Specification for 4-wire PWM Controlled Fans

for additional details on the fan

specification.

Section	Page
Contents	3
Figures	6
Tables	7
Revision History	8
1 Introduction	9
1.1 Document Goals and Scope	9
1.1.1 Importance of Thermal Management	9
1.1.2 Document Goals	9
1.1.3 Document Scope	10
1.2 References	11
1.3 Definition of Terms	12
2 Processor Thermal/Mechanical Information	15
2.1 Mechanical Requirements	15
2.1.1 Processor Package	15
2.1.2 Heatsink Attach	17
2.1.2.1 General Guidelines	17
2.1.2.2 Heatsink Clip Load Requirement	17
2.1.2.3 Additional Guidelines	18
2.2 Thermal Requirements	18
2.2.1 Processor Case Temperature	18
2.2.2 Thermal Profile	19
2.2.3 TCONTROL	20
2.3 Heatsink Design Considerations	21
2.3.1 Heatsink Size	22
2.3.2 Heatsink Mass	22
2.3.3 Package IHS Flatness	22
2.3.4 Thermal Interface Material	23
2.4 System Thermal Solution Considerations	23
2.4.1 Chassis Thermal Design Capabilities	23
2.4.2 Improving Chassis Thermal Performance	23
2.4.3 Summary	24
2.5 System Integration Considerations	24
3 Thermal Metrology	25
3.1 Characterizing Cooling Performance Requirements	25
3.1.1 Example	26
3.2 Processor Thermal Solution Performance Assessment	27
3.3 Local Ambient Temperature Measurement Guidelines	27
3.4 Processor Case Temperature Measurement Guidelines	30
4 Thermal Management Logic and Thermal Monitor Feature	31
4.1 Processor Power Dissipation	31
4.2 Thermal Monitor Implementation	31
4.2.1 PROCHOT# Signal	32
4.2.2 Thermal Control Circuit	32
4.2.3 Operation and Configuration	33
4.2.4 On-Demand Mode	34
4.2.5 System Considerations	34
4.2.6 Operating System and Application Software Considerations	35
4.2.7 On-Die Thermal Diode	35
4.2.7.1 Reading the On-Die Thermal Diode Interface	35
4.2.7.2 Correction Factors for the On-Die Thermal Diode	36
4.2.8 THERMTRIP# Signal	37
4.2.8.1 Cooling System Failure Warning	37
5 Intel® Thermal/Mechanical Reference Design Information	39
5.1 Intel Validation Criteria for the Reference Design	39
5.1.1 Heatsink Performance Target	39
5.1.2 Acoustics	40
5.1.3 Altitude	40
5.1.4 Reference Heatsink Thermal Validation	41
5.1.5 Fan Performance for Active Heatsink Thermal Solution	41
5.2 Environmental Reliability Testing	42
5.2.1 Structural Reliability Testing	42
5.2.1.1 Random Vibration Test Procedure	42
5.2.1.2 Shock Test Procedure	42
5.2.2 Power Cycling	44
5.2.3 Recommended BIOS/Processor/Memory Test Procedures	44
5.3 Material and Recycling Requirements	44
5.4 Safety Requirements	45
5.5 Geometric Envelope for ATX Intel® Reference Thermal Mechanical Design	45
5.6 ATX Reference Thermal Mechanical Solution for the Intel® Pentium® 4 Processor in the 775–Land LGA Package	46
5.7 Reference Attach Mechanism	48
5.7.1 Structural Design Strategy	48
5.7.2 Mechanical Interface to the Reference Attach Mechanism	49
6 Acoustic Fan Speed Control	53
6.1 Acoustic Fan Speed Control	53
6.2 Thermal Solution Design	53
6.2.1 Compliance to Thermal Profile	53
6.2.2 Determine Thermistor Set Points	53
6.2.3 Minimum Fan Speed Set Point	54
6.3 Board and System Implementation	55
6.3.1 Choosing Fan Speed Control Settings	55
6.3.1.1 Temperature to begin Fan Acceleration	56
6.3.1.2 Minimum PWM Duty Cycle	58
6.4 Combining Thermistor and Thermal Diode Control	59

Intel 640 User Guide - Page 41

Reference Heatsink Thermal Validation, Fan Performance for Active Heatsink Thermal Solution

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