Intel QX9770 Design Guidelines - Page 97

Legacy Fan Speed Control

Thermal and Mechanical Design Guidelines

97

Appendix E

Legacy Fan Speed

Control

A motherboard design may opt to use a SIO or ASIC based fan speed control device

that uses the existing look up or state based fan speed control.

The fan speed control implementations consist of the following items

•

A motherboard designed with a fan speed controller with the following

functionality:

⎯

PWM fan control output

⎯

Remote digital thermal sensor measurement capability over the PECI bus.

•

A motherboard with a 4 pin fan header for the processor heatsink fan.

•

Processor heatsink with 4–wire PWM controlled Fan.

A thermistor in the fan hub is recommended, but not a requirement.

The

reference solution and the Boxed Processor will implement a thermistor into the

design.

The following sections will discuss the necessary steps to implement Legacy Fan

Speed Control.

E.1

Thermal Solution Design

The first step is to select or design a processor thermal solution that meets the

thermal profile for the processor.

See Section

2.2.2 for the definition of the thermal

profile and consult the processor datasheet for the specific values.

The designer needs to ensure that when the heat sink fan is operating at full speed

the thermal solution will meet the T

C-MAX

limits at TDP.

The slope of the thermal

profile will allow the designer to make tradeoffs in thermal performance versus the

inlet temperature to the processor fan heatsink.

E.1.1

Determine Thermistor Set Points

A thermistor implemented in the hub of a fan is a first level of fan speed control.

It

provides an easy and cost effective means to begin acoustic noise reduction.

It will,

by design, run the fan at an appropriate speed based on the ambient conditions.

Chapter

5 discussed in detail the reference thermal solution, including the target

Ψ

CA

,

fan speed based on temperature to ensure that T

C-MAX

is not exceeded for TDP power

at a given ambient temperature.

The resulting variable speed fan (VSF) curve is the

upper limit on fan speed.

The benefit of this upper limit will become more apparent when the fan speed

controller is responding to the digital thermal sensor.

Section	Page
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	11
2 Processor Thermal/Mechanical Information	13
2.1 Mechanical Requirements	13
2.1.1 Processor Package	13
2.1.2 Heatsink Attach	15
2.1.2.1 General Guidelines	15
2.1.2.2 The Pump Assembly Clip Load Requirement	15
2.1.2.3 Additional Guidelines	16
2.2 Thermal Requirements	16
2.2.1 Processor Case Temperature	16
2.2.2 Thermal Profile	17
2.2.3 TCONTROL	18
2.3 Heatsink Design Considerations	19
2.3.1 Heatsink Size	20
2.3.2 Package IHS Flatness	20
2.3.3 Thermal Interface Material	21
2.4 System Thermal Solution Considerations	21
2.4.1 Chassis Thermal Design Capabilities	21
2.4.2 Improving Chassis Thermal Performance	21
2.4.3 Summary	22
2.5 System Integration Considerations	22
3 Thermal Metrology	23
3.1 Characterizing Cooling Performance Requirements	23
3.1.1 Example	25
3.2 Processor Thermal Solution Performance Assessment	26
3.3 Local Ambient Temperature Measurement Guidelines	26
3.4 Processor Case Temperature Measurement Guidelines	29
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 Thermal Monitor 2	33
4.2.4 Operation and Configuration	34
4.2.5 On-Demand Mode	35
4.2.6 System Considerations	35
4.2.7 Operating System and Application Software Considerations	36
4.2.8 THERMTRIP# Signal	36
4.2.9 Cooling System Failure Warning	36
4.2.10 Digital Thermal Sensor	37
4.2.11 Platform Environmental Control Interface (PECI)	38
5 Intel Thermal/Mechanical Reference Design Information	39
5.1 Validation Results for the ATX Reference Design	39
5.1.1 Heatsink Performance	40
5.1.2 Acoustics	40
5.1.3 Altitude	41
5.1.4 Reference Heatsink Thermal Validation	41
5.1.5 Fan Motor Performance	42
5.1.6 Pump Motor Performance	43
5.2 Environmental Reliability Testing	44
5.2.1 Structural Reliability Testing	44
5.2.1.1 Random Vibration Test Procedure	44
5.2.1.2 Shock Test Procedure	45
5.2.2 Power Cycling	46
5.2.3 Reliability Testing	46
5.2.3.1 Tubing Material Selection	48
5.2.3.2 Reservoir Sizing	48
5.2.3.3 Reliability Test Results	50
5.2.4 Recommended BIOS/CPU/Memory Test Procedures	51
5.3 Material and Recycling Requirements	52
5.4 Safety Requirements	52
5.5 Geometric Envelope for Intel Reference ATX Thermal Mechanical Design	52
5.6 Reference Attach Mechanism	54
5.7 Socket and Voltage Regulation Cooling Strategy	55
6 Intel® Quiet System Technology (Intel® QST)	57
6.1 Intel® Quiet System Technology Algorithm	57
6.1.1 Output Weighting Matrix	58
6.1.2 Proportional-Integral-Derivative (PID)	58
6.2 Board and System Implementation of Intel® Quiet System Technology	60
6.3 Intel® QST Configuration & Tuning	62

Intel QX9770 Design Guidelines - Page 97

Appendix E, Legacy Fan Speed, Control, Thermal Solution Design

Page 97 highlights