Intel 640 User Guide - Page 91

Balanced Technology Extended (BTX) System Thermal Considerations

R

Thermal/Mechanical Design Guide

91

Appendix F Balanced Technology

Extended

(

BTX) System

Thermal Considerations

There are anticipated system operating conditions in which the processor power may be low but

other system component powers may be high. If the only Fan Speed Control (FSC) circuit input

for the Thermal Module Assembly (TMA) fan is from the processor diode, then the fan speed and

system airflow is likely to be too low in this operating state. Therefore, it is recommended that a

second FSC circuit input be acquired from an ambient temperature monitor location within the

system.

The location of the System Monitor thermal sensor is best determined through extensive system-

level numerical thermal modeling or prototype thermal testing. In either case, the temperature of

critical components or the air temperature near critical components should be assessed for a range

of system external temperatures, component powers, and fan speed operating conditions. The

temperature at the selected location for the System Monitor Point should be well correlated to the

temperatures at or near critical components. For instance, it may be useful to monitor the

temperature near the PSU airflow inlet, near the graphics add-in card, or near memory.

The final system integrator is typically responsible for ensuring compliance with the component

temperature specifications at all operating conditions and, therefore, should be responsible for

specifying the System Monitor thermal sensor location. However, it is not always possible for a

board supplier – especially a channel board supplier – to know the system into which a board will

be installed. It is, therefore, important for BTX board suppliers to select a System Monitor

thermal sensor location that will function properly in most systems.

A BTX system should be designed such that the TMA exhaust is the primary airflow stream that

cools the rest of the system. The airflow passes through the chipset heatsink and its temperature

will rise as the memory controller chipset power increases. Since chipset power will increase

when other subsystems (e.g., memory, graphics) are active, a System Monitor thermal sensor

located in the exhaust airflow from the chipset heatsink is a reasonable location.

It is likely that a thermal sensor that is not mounted above the board and in the chipset exhaust

airflow will reflect board temperature and not ambient temperature. It is therefore recommended

that the Thermal sensor be elevated above the board.

The thermal sensor location and elevation are reflected in the Flotherm thermal model airflow

illustrations (see Figure 43 and Figure 44).The Intel

®

Boxed Boards in BTX form factor have

implemented a System Monitor thermal sensor. The following thermal sensor or its equivalent can

be used for this function:

Part Number: C83274-002

BizLink USA Technology, Inc.

44911 Industrial Drive

Fremont, CA 94538 USA

(510)252-0786 phone

(510)252-1178 fax

[email protected]

Part Number: 68801-0170

Molex Incorporated

2222 Wellington Ct.

Lisle, IL

60532

1-800-78MOLEX phone

1-630-969-1352 fax

[email protected]

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 91

Appendix F Balanced Technology, Extended, BTX System, Thermal Considerations

Page 91 highlights