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Intel QX9770 Design Guidelines - Page 100

E.2.1.1, Temperature to Begin Fan Acceleration, Fan Speed Control

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Legacy Fan Speed Control These are the minimum parameters required to implement acoustic fan speed control. See Figure 59 for an example. There may be vendor specific options that offer enhanced functionality. See the appropriate vendor datasheet on how to implement those features. Figure 59. Fan Speed Control Full Speed 100 % Fan Speed (RPM) Fan Speed (% PWM Duty Cycle) Min Speed X % TLOW TCONTROL Diode Temperature (°C) E.2.1.1 Temperature to Begin Fan Acceleration The first item to consider is the value for TLOW. The FSC device needs a minimum temperature to set as the threshold to begin increasing PWM duty cycle to the fan. The system designer might initially consider a small temperature range (TCONTROL - TLOW = TRANGE), 5°C to accelerate the fan. That would delay the fan accelerating for the longest time after an increase in TSENSOR. There are a number of issues that should be considered with this strategy • There is little granularity in the fan speeds. For each 1°C of increase in diode temperature = 20% jump in PWM duty cycle % • Fan speed oscillation as the thermal solution chases the digital thermal sensor temperature • Having TSENSOR overshoot TCONTROL and the thermal profile causing the Thermal Control Circuit to activate to reduce the temperature. • In extreme cases Thermtrip# activates and shuts down the processor The first two cases can create a poor acoustic response for the user. The third case the user could notice a drop in performance as the thermal control circuit reduces the power. The Figure 60 is an example of this situation. The system begins at idle and the Maxpower program is started at 65% workload. 100 Thermal and Mechanical Design Guidelines

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