Intel QX9770 Design Guidelines - Page 20

LGA775 Socket Heatsink Loading

20

Thermal and Mechanical Design Guidelines

Passive heatsink

solutions require in-depth knowledge of the airflow in the chassis.

Typically, passive heatsinks see lower air speed.

These heatsinks are therefore

typically larger (and heavier) than active heatsinks due to the increase in fin surface

required to meet a required performance.

As the heatsink fin density (the number of

fins in a given cross-section) increases, the resistance to the airflow increases: it is

more likely that the air travels around the heatsink instead of through it, unless air

bypass is carefully managed.

Using air-ducting techniques to manage bypass area

can be an effective method for controlling airflow through the heatsink.

2.3.1

Heatsink Size

The size of the heatsink is dictated by height restrictions for installation in a system

and by the real estate available on the motherboard and other considerations for

component height and placement in the area potentially impacted by the processor

heatsink. The height of the heatsink must comply with the requirements and

recommendations published for the motherboard form factor of interest. Designing a

heatsink to the recommendations may preclude using it in system adhering strictly to

the form factor requirements, while still in compliance with the form factor

documentation.

For the ATX/microATX form factor, it is recommended to use:

•

The ATX motherboard keep-out footprint definition and height restrictions for

enabling components, defined for the platforms designed with the LGA775 socket

in

Appendix G of this design guide.

•

The motherboard primary side height constraints defined in the

ATX Specification

V2.2

and the

microATX Motherboard Interface Specification V1.2

found at

http://www.formfactors.org/

.

The resulting space available above the motherboard is generally not entirely available

for the heatsink. The target height of the heatsink must take into account airflow

considerations (for fan performance for example) as well as other design

considerations (air duct, etc.).

For BTX form factor, it is recommended to use:

•

The BTX motherboard keep-out footprint definitions and height restrictions for

enabling components for platforms designed with the LGA77 socket in

Appendix G

of this design guide.

•

An overview of other BTX system considerations for thermal solutions can be

obtained in the

Balanced Technology Extended (BTX) System Design Guide v1.0

found at

http://www.formfactors.org/

.

2.3.2

Package IHS Flatness

The package IHS flatness for the product is specified in the datasheet and can be used

as a baseline to predict heatsink performance during the design phase.

Intel recommends testing and validating heatsink performance in full mechanical

enabling configuration to capture any impact of IHS flatness change due to combined

socket and heatsink loading. While socket loading alone may increase the IHS

warpage, the heatsink preload redistributes the load on the package and improves the

resulting IHS flatness in the enabled state.

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 20

Heatsink Size, 2.3.2 Package IHS Flatness, Passive heatsink

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