Date: December 1998 Revision: THIS SPECIFICATION [DOCUMENT] PROVI
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Profile Duct Design Guidelines
Date: December 1998 Revision:
THIS SPECIFICATION [DOCUMENT] PROVIDED WITH WARRANTIES WHATSOEVER, INCLUDING WARRANTY MERCHANTABILITY, NONINFRINGEMENT, FITNESS PARTICULAR PURPOSE, WARRANTY OTHERWISE ARISING PROPOSAL, SPECIFICATION SAMPLE. Intel disclaims liability, including liability infringement proprietary rights, relating information this specification. license, express implied, estoppel otherwise, intellectual property rights granted herein. Copyright 1998 Intel Corporation. rights reserved. Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, 97124-6497
Profile Duct Design Guidelines
Profile Duct Design Guidelines Introduction. Ducting Philosophy Chassis Recommendations
Venting
3.1.1 3.2.1 3.2.2 3.2.3 Vent Fabrication. Power Supply Drive Bays Cabling
Keep Areas.
Duct Design Recommendations.
Thermal Design
4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.2.1 4.2.2 4.2.3 4.2.4 4.3.1 4.3.2 4.3.3 4.4.1 Thermal Requirements. Volume Airflow Airflow Through Duct. Inlet Vent Design. Duct Shape Duct Ribbing Temperature Duct Mounting. Mounting. Location Ribbing Cabling. Vent Hole Diameter Shielding Properties. Material. Designing Variable Back Panel Lengths
Structural Design
Design
Other Design Considerations.17
Assembly Recommendations.
Duct Component Assembly.18 Installation Profile Duct
Heat Sink Design Recommendations.
Profile Heat Sink.21 Heat Sink Attach Mechanism
Appendix Thermal Test Setup Appendix Structural Validation Report Appendix Test Results Appendix Profile Heat Sink Drawings
Profile Duct Design Guidelines
Introduction
following document provides information designing, manufacturing, assembling Profile Duct system Profile Duct Motherboard Chassis Ingredients Specifications. Although this guideline will single reference design example, Duct system designer should adapt this design meet their specific system design needs.
Ducting Philosophy
thermal demands today's computer systems increases, becomes necessary manage both internal chassis temperature airflow Core Logic components (processor, chipset, graphics, graphics controller, memory). order meet increased thermal demands, additional heat sinks increased velocities required cooling Core Logic components. recommended low-cost alternative this Profile Duct micro-ATX systems. Profile Duct impinges high velocity from outside chassis directly Core Logic components.
Chassis Recommendations
Venting Profile Duct system requires inlet vent micro-ATX chassis. internal within Duct, pulls cool exterior through vent into duct. from internal then impinges Core Logic components. order balance airflow containment, size vent hole openings spacing between holes limited. metric gauging venting perforated metal percent open. This defined open area (the open area summation hole areas) divided total area (area holes plus solid metal between holes). This averaged value. Profile Duct able deliver full performance, vent area must minimum maximum open. containment prevent dust clogging vent, hole dimensions must range 0.12 inches 0.17 inches (3.0 mm). Section 4.1.1 additional details. 3.1.1 Vent Fabrication venting fabricated number ways. primary methods Punch vent holes back panel shown Figure Incorporate perforated sheet metal hole pattern with gasket maintain chassis shielding effectiveness, Figure
Profile Duct Design Guidelines
Profile Duct Mounting
Add-in Card slots
Inlet Vent Connector area Figure Typical Back Panel with Open Hole Pattern
Figure Exploded View Gasket Pre-Stamped Bracket (hole pattern same shown Figure When using pre-fabricated hole pattern, extremely important have proper grounding around perimeter chassis opening between perforated mounting bracket chassis opening. ground point spacing should greater than 0.17 inches (4.3 mm). These grounding solutions achieved using compliant electrically conductive material stamped metal bracket, which spring fingers spacing 0.17 inches less.
Keep Areas There keep zones required fitting Profile Duct micro-ATX chassis. Profile Duct style intended chassis with power supplies that above side motherboard. specific keep outs chassis include power supply, drive bays, cabling.
Profile Duct Design Guidelines
3.2.1 Power Supply majority chassis with standard power supplies will accommodate Profile Duct system. following list guidelines power supplies: When using micro-ATX chassis, power supply should have mounted internally. recommended airflow direction exhaust from power supply rear chassis. inlet vent power supply should front side power supply, side that would blocked Duct. recommended position power supply mount side motherboard. 3.2.2 Drive Bays drive bays should mounted away from motherboard possible simplify cabling. minimum, drive bays peripherals should interfere with micro-ATX motherboard keep specifications. 3.2.3 Cabling optimal cabling placement, power connectors should located shaded areas shown Figure addition, drives should located from motherboard possible order allow easy connection cables. Additional assembly considerations discussed Section
Figure Optimal Placement Power Connectors Profile Duct Design Guidelines
Duct Design Recommendations
Thermal structural test validation methodology found Appendix. following sections provide summary recommendations complying with Profile Duct specifications. Thermal Design primary purpose Profile Duct cool Processor Core Logic components most efficiently lowest cost. primary thermal advantages Duct that provides high velocity lowest possible temperature directly Core Logic components. close proximity Duct's Core Logic components allows impinge directly processor's heat sink well other Core Logic components. following sections provide specific information optimizing performance Profile Duct. 4.1.1 Thermal Requirements Profile Duct must cool Processor Core Logic components their required Junction Case Temperatures. There four primary conditions that Duct reference design must meet (see Appendix thermal test loading details): Provide sufficient cooling require heat sinks Core Logic components, except processor. negatively impact cooling remainder chassis (hard drives, add-in cards, power supply). Thermal validation testing must utilize maximum power dissipating software each Core Logic components. micro-ATX system validation testing must heavily loaded. Test under worst case environmental conditions, typically 35°C outside chassis. should noted that when thermal testing with fixed speed fans, testing performed ambient temperatures lower than 35°C, then extrapolated 35°C. example, test performed using fixed speed speed control). test performed 26°C ambient environment. results scaled 35°C adding difference (35°C 26°C 9°C) results measured 26°C.
Profile Duct Design Guidelines
4.1.2 Volume Airflow determined that meet four conditions outlined Section 4.1.1 requires minimum Cubic Feet Minute (CFM) volumetric airflow from Duct. system configuration severe those listed, volume airflow related speed reduced, would need revalidated. Profile Duct specifications require that basic geometry inlet vent duct prevent Duct from being able provide airflow Core Logic components, when using typical axial fans Duct. This does mean that lower speed fans fans that speed control used Duct. Another design option integrate directly Duct. volume airflow measured inlet vent into micro-ATX chassis. power supply operating conditions outlined Section 4.1.1. method estimating volume airflow attaching collar around intake vent measuring average velocity into collar area. collar area measured converted square feet. This area multiplied average velocity into collar resulting measurement volume airflow (Cubic Feet Minute CFM). collar should inches tall block airflow into vent. velocities typically measured with hot-wire anemometers. Duct speed control circuitry reduce speed when operated less than 35°C environments, volume airflow requirement reduced while operating lower temperature. primary reason using speed control reduce acoustic noise produced Duct. example this Duct lower speed when inlet temperature Duct 25°C. typical approach would reduce voltage from volts (nominal) volts. inlet temperature should rise higher specified value 35°C, speed increased volts (nominal). Equation used estimate change sound pressure level different speeds. Equation (change measured 50*LOG(RPM1/RPM2) where, decrease/increase sound pressure level, RPM1 rotational speed fan, RPM2 rotational speed fan, example, voltage reduced from nominal value volts volts, rotational speed reduced factor 0.58, resulting decrease from original sound pressure level. Caution should exercised determining starting voltage speed voltage setting fan. Typically minimum starting voltage volt
Profile Duct Design Guidelines
(nominal) axial volts. This value needs worked with supplier. more information speed control, Profile Duct Ingredients Specification, Section 4.1. 4.1.3 Airflow Through Duct Airflow restrictions should minimized within Profile Duct maximum performance. three basic guidelines designing interior Profile Duct are: inlet vent pattern that least restrictive airflow, that does cause problems smooth gradual transitions minimize flow impedance's Internal structural ribbing should follow contours airflow 4.1.4 Inlet Vent Design inlet vent geometry Profile Duct largest affect volumetric airflow through Profile Duct. order balance airflow containment, size vent hole openings spacing between holes limited. metric gauging venting perforated metal percent open. This defined open area (the open area summation hole openings given area) divided total area (area holes plus solid metal between holes). This averaged value. Profile Duct able deliver full performance, vent area must minimum maximum open. containment prevent dust from clogging inlet vent, hole dimensions must range 0.12 inches 0.17 inches (3.0 mm). Section additional details. metric understanding effect vent geometry flow through vent static pressure drop moves through vent. This several pressure drops that Duct must overcome. This pressure drop thought drag loss typically measured inches water. vent that uses perforated sheet metal, method comparing pressure drops shown Equation Table
Equation
PDROP (ATOTAL)2
where, PDROP Static pressure drop, inches water Head Loss Coefficient, Table ATOTAL Total unblocked vent area,
Table Open
Profile Duct Design Guidelines
Equation used comparative purposes only. Additional coefficients must included determine actual pressure drop. percent open given perforated vent area increases, associated drops dramatically, especially going from open open, Table even larger factor ATOTAL, which vent area that must flow through, since this term squared then divided into term. percent open perforated sheet metal limited containment requirements, ability manufacture perf pattern. Vent areas using greater than open perforated sheet metal more difficult thus more expensive produce result problems. Another example pre-fabricated vent pattern shown Figure Profile Duct airflow requirements using staggered hole pattern shown Figure percent open staggered hole pattern calculated using Equation where diameter hole. hexagonal pattern shown Figure equation calculating percent open using hexagonal hole pattern shown Equation where must equal less than 0.170 inches (4.3 mm). staggered square pattern shown Figure associated percent open calculated using Equation where diagonal square again must less than 0.170 inches (4.3 containment.
Duct Chassis Rear Panel with rectangular Thin Preplate Metal Vent shield
Figure Example Pre-Fabricated Vent Pattern.
Profile Duct Design Guidelines
Figure Vent Dimensions Staggered Circular Hole Pattern Equation Percent Open Staggered Circular Hole Pattern
*D2*100 (2*L*W)
Figure Vent Dimensions Staggered Hexagonal Hole Pattern Equation Percent Open Hexagonal 1.732*G^2)
(519.6*S^2) (5.196*S^2 6*S*G
Profile Duct Design Guidelines
Figure Vent Dimensions Staggered Square Hole Pattern Equation Percent Open Staggered 100*S2 Square Hole Pattern
4.1.5 Duct Shape Profile Duct shape important minimizing static backpressure that must overcome. general, Duct should provide smooth airflow transitions whenever there varying cross-sections. Examples these smooth transitions shown Figure Gradual Curve from Vent Inlet
Corners with Radii
Figure Examples Gradual Cross Section Transitions
Profile Duct Design Guidelines
4.1.6 Duct Ribbing When using ribbing strengthen Duct, ribbing should always follow airflow contours fan, shown Figure Internal Ribs
Airflow Into Duct
Figure Structural Ribbing Follows Airflow Contours 4.1.7 Temperature Profile Duct utilizes cool external provide lowest possible temperature Processor Core Logic components. typical temperature within micro-ATX systems 10°C 20°C higher than temperature outside chassis. Profile Duct provides 10°C 15°C advantage over typical system. When power supply positioned left Duct viewed from rear chassis), there potential temperature rise Core Logic components. This results from recirculation exhaust from power supply, which mixed with cool exterior outside chassis before being pulled into Duct. determined that recirculation this configuration problem unless chassis less than equal inches from wall. This likely happen result cabling from rear chassis. Another power supply placement scenario above Profile Duct, Figure this case more likely that recirculation will problem. solution prevent this type recirculation external duct shown Figure
Profile Duct Design Guidelines
Figure Exhaust Recirculation from Power Supply Profile Duct
Inlet Duct
Figure Inlet Duct Mounted Duct Intake Vent Structural Design order prevent damage system components, Profile Duct must withstand environmental shipping handling requirements. shipping requirements vary different system integrators. following recommendations based tests using Intel environmental shipping requirements found Appendix Profile reference design meets Intel shock vibration requirements shown slow motion video still Figure
Profile Duct Design Guidelines
Duct Shock Direction
Memory Modules Pentium®II Cartridge
Figure Negligible Duct Deflection Using Motherboard Bracket (30-G trapezoidal Drop Test) 4.2.1 Duct Mounting both computer simulations experiments, Profile Duct required support from back panel rear support bracket shown Figure motherboard support bracket helps prevent excessive back panel flexure. Although reference design used rear support bracket motherboard bracket, motherboard bracket required chassis. Testing should used determine bracket necessary not. Please note that computer model duct simplified allow faster simulation times. Shock tests done without rear bracket supports cause back panel permanently deform Profile Duct system components.
Back Panel Mount Motherboard Support Bracket
Figure Fully Supported Profile
Profile Duct Design Guidelines
addition holding Profile Duct place, Duct should easily removable order replace system components. access processor core components done using snap rear bracket design screws back panel. assembly procedure Duct shown Section 4.2.2 Mounting There number ways mount duct. order simplify duct assembly, recommended approach mounting using snaps molded into duct. snap used reference design provides locking engagement when downward force applied shown Figure There four molded pins that interact with mounting holes prevent movement other axes, Figure Load from
retains planar directions
downward load forces snap engage toward fan. Figure Snap Lock Feature Reference Design Retention
4.2.3 Location offset toward add-in cards card improve airflow those components provide hard drive cable clearances. This beneficial compact systems such micro-ATX, Figure
Profile Duct Design Guidelines
Figure Location Reference Design 4.2.4 Ribbing Profile Duct reference design uses ribbing prevent Duct from flexing. structural ribs inches tall they parallel airflow. order minimize airflow resistance, Duct should contain more than four ribs. Design 4.3.1 Cabling order minimize Electro-Magnetic Interference (EMI) radiation, cable should plugged into power supply harness. Plugging Duct directly into motherboard result increase EMI. 4.3.2 Vent Hole Diameter Shielding Properties intake vent Profile Duct requires hole openings range 0.12 inches 0.17 inches (3.0 mm). maximum dimension hole openings defined greatest distance from vertices given hole. additional containment work required when using stamped vent pattern back panel chassis. case using prefabricated screen hole pattern that fits chassis, steps must taken maintain chassis shielding effectiveness. This achieved ways. Electrical contact between intake vent chassis must maintained either:
Profile Duct Design Guidelines
Continuously with gasket similar conductive compliant material discrete contact points exceed 0.17 inches (4.3 apart. achieving this dimples. 4.3.3 Material radiation increased when using metal design Profile Duct. Metal good structural material, cause related problems recommended. example this metal plate bottom duct. Radiation levels increased when using metal plate bottom Duct (See Figure design example). Additional testing revealed that metal mounting brackets wire supports showed little increase radiation. best design configuration minimal radiation design with non-conductive material such plastic. Metal Plate (shaded)
Plastic Duct with Small Metal Bracket Does Impact emissions
Design Good Design Figure Good Design Examples
Other Design Considerations 4.4.1 Designing Variable Back Panel Lengths Since mounting scheme Profile Duct uses back panel, Duct system designer must accommodate variable back panel lengths. plane back panel either located line with panel line with ends add-in card brackets shown Figure order accommodate varying back panel locations, bracket used shown Figure
Profile Duct Design Guidelines
Figure Back Panel Location with respect Datum Specification
Back Panel with Minimum length
Back Panel with Maximum length
Duct attaches bracket
Figure Mounting Bracket Design Variations Accommodate Back Panel Locations
Assembly Recommendations
Duct Component Assembly duct component assembly will vary depending design. following example based Profile Duct reference design. order reduce tooling complexity cost, Duct reference design four components: bottom duct, cover, fan, threaded inserts. duct, bottom duct, assembled using snaps since they designed into plastic tooling easily. threaded inserts captive nuts), used assemble duct into chassis, should pre-assembled bottom duct. primary components assembled basic steps shown Figure
Profile Duct Design Guidelines
Step
Step Figure Duct Component Assembly. Installation Profile Duct assembly Duct chassis requires screwing rear bracket motherboard inserting screwing Duct into back panel. Duct reference design uses rear bracket that assembled middle stand-offs. rear bracket should assembled directly after motherboard assembled since prevents cables from running between duct processor core logic components. Once cabling been assembled, Duct should inserted. Duct will either have studs nuts pre-assembled Duct body. After studs placed through holes shown Figure Duct snapped into rear bracket.
Profile Duct Design Guidelines
Figure Assembly Rear Support Bracket Motherboard
Figure Duct Insertion into Chassis Assembly.
Profile Duct Design Guidelines
Heat Sink Design Recommendations
Profile Heat Sink order comply with Profile Duct specifications, profile heat sink required. profile heat sink offers lower cost weight advantages over traditional heat sink. Drawings heat sink found Appendix
Figure profile Heat Sink Assembled Pentium® cartridge. Heat Sink Attach Mechanism 6.2.1 SECC profile heat sink utilizes same attach mechanisms standard heat sink thermal plate. clip riv-screw holes used profile heat sink currently thermal plate, shown Figure
Holes Used Heat Sink Attach
Figure Pentium Thermal Plate Mounting Holes
Profile Duct Design Guidelines
6.2.2 SECC2 When using SECC2 processor form factor, heat sink attach mechanism must also within motherboard keep areas found Profile Duct Motherboard Chassis Specification. current reference design SECC2 heat sink will interfere with Duct. Alternative solutions SECC2 heat sink attach system will published separate document. application note related information found following site:
DUCT
NOTE: Interference with Heat Sink Attach Clips
Figure Interference current Heat Sink Attach Clips with Duct
Profile Duct Design Guidelines
Appendix Thermal Test Setup
Introduction
This document provides micro-ATX system configuration, temperature airflow sensor locations test Profile Duct system. configuration intended represent standard desktop system. Although following thermocouple airflow sensors minimum required validate Profile Duct system, additional sensors added provided they impede airflow within system.
System Configuration
following necessary components component placement testing Profile Duct system:
Component
Processor Memory Graphics Audio Modem Riser Processor Heat Sink Floppy Drive Primary Hard Drive Secondary Hard Drives 5.25" Drive Power Supply Motherboard Chassis
Type
Klamath Mhz, i740 Graphics Card Full Length (slot Profile ATXV1 Watt Load Card Watt Load Card Standard SCSI 7200 watt standby) Seattle (ATX) Maui (micro-ATX) Midtower microATX
Software Configuration
Appropriate power virus for: CPU, Memory, Chipset, Graphics. These tests concurrently.
Profile Duct Design Guidelines
Thermocouple Sensor Locations
There several thermocouple airflow sensors that required validate system. left right directions oriented based back panel facing north. Airflow Sensor Locations
Flow Velocity Direction
Sensor
Processor Processor Processor Processor Memory
Location
heat sink, right side heat sink, left side Bottom heat sink, left side Bottom heat sink, right side front first memory slot, parallel memory, center memory card front first memory slot, center memory card back last memory slot, center memory card back first memory slot, center memory card left side memory slots close motherboard possible right side memory slots close motherboard possible 0.2" Above Chipset, Behind inlet vent, left side vent Behind inlet vent, center vent Behind inlet vent, parallel motherboard, right side vent front inside power supply vent front outside power supply vent Below processor chip airflow backside card
Memory Memory Memory Memory
Memory
Chipset Inlet Inlet Inlet
Power Supply Power Supply
Profile Duct Design Guidelines
Direction Orientation Test Setup:
Right Side 1.1.1.1.1.1 1.1.1.1.1.3 1.1.1.1.1.5
Left Side
Processor Core Logic Component Area dashed lines indicate that probes hidden behind object
Profile Duct Design Guidelines
Duct Vent (Fan Duct perf pattern shown clarity)
Power Supply Location
Add-In Card Area
Profile Duct Design Guidelines
Thermocouple Locations
Sensor
Processor
Location
Processor plate temperature, center thermal plate Chipset Chipset case temperature, center chip Memory Ambient 0.1"-0.2" above memory right side Memory Ambient 0.1"-0.2" above memory left side Memory Exit 0.1" above motherboard right side Memory Exit 0.1" above motherboard left side Add-In Card 0.75" above add-in cards Ambient towards back chassis Add-In Card 0.75" above add-in cards Ambient towards middle chassis Add-In Card Internal from bottom Ambient motherboard in-between cards Add-In Card 0.75" above add-in cards Ambient towards front chassis Hard Drive Case active hard drive case lower case upper case Power Supply 0.5" front power Exhaust supply vent chassis outside Vent 0.5" front vent Internal Power 0.25 0.5" front internal Supply power supply vent Case processor case Board back card center processor Processor Local 0.25" above center heat sink Chipset Local 0.25" above center chipset External Ambient External away from chassis
Profile Duct Design Guidelines
Processor Area Core Logic Area
Add-In Card Area
Profile Duct Design Guidelines
Back Panel Area
Add-In Card Area
Profile Duct Design Guidelines
Load Card Configuration
Load Card watt distributed load)
Load Card watt distributed load)
Profile Duct Design Guidelines
Appendix Structural Validation Report
Executive Summary
Profile Duct reference design passed shock vibration tests Duct requires support both front back duct
Empirical Validation
Profile Duct empirically tested ensure design necessary shock vibration reliability requirements. following sections describe test parameters results Profile Duct reference design. Failure Criteria: Duct failure criteria were: visual damage duct other system component system must electrically function before after each test Duct must processor core components: processor, chipset, memory, graphics card. Test Results Shock Profile Duct reference design passed structural failure criteria drop directions shock test. test consisted drops: positive negative directions each axis shown Figure Tests that were with rear support bracket showed that Duct processor heat sink. Although system still functioned, long-term reliability processor have been negatively impacted.
Rear Support Bracket
Front Support Bracket
Figure Three Primary Test Axis
Profile Duct Design Guidelines
Vibration Profile Duct reference design also passed structural failure criteria directions random vibration test. vibration tests same axis used shock test. Components Used Profile Duct Profile Duct with metal front bracket plastic rear bracket used perform validation tests shown Figure body Duct made from urethane mold order provide quick prototypes. weaker properties urethane over plastics, urethane duct considered worst case structural sample. Motherboard motherboard Pentium processor with chipset. There were add-in cards used since cards would help stiffen back panel chassis. Chassis Profile Duct tested production version mini-tower chassis named Galileo chassis. Galileo chassis consists power supply mounted directly over Duct with clearance approximately 0.07"0.10". Test Settings Shock Test shock test consists rigidly mounting assembled chassis shock table. standard system level shock settings are: Pulse Type: Trapezoidal Acceleration: Duration: Random Vibration Test vibration test consists rigidly mounting assembled chassis vibration table. standard system level random profile vibration settings are: Random Profile: .001 0.01 (slope shown figure 0.01 (flat) Input acceleration 2.20 minutes axis axes samples
Profile Duct Design Guidelines
Figure Random Vibration Input Ramp.
Conclusion
validation tests indicated current Profile Duct provides robust structural design ensure reliable product. critical parameters success Duct design consists providing support from both back panel motherboard support bracket. deviations from this support structure must properly tested.
Profile Duct Design Guidelines
Appendix Test Results
Criteria: Profile Duct should compromise performance existing chassis. Test Configuration: System board: Chassis: Processor Speed: Duct:
Seattle mother board Galileo Minitower ATX* 400, 450, Plastic section metal base
Tested both open chassis closed chassis configuration GTEM GHz. Test looked variations base configuration with Duct compared configuration without Duct. Vent pattern test: open perforated vent pattern with .170 inch (4.3 diameter holes added back panel chassis Basic Equation Hole Diameter (max): 300/f(MHz) wave length, meters frequency, (ideal hole diameter) (max hole diameter) Note: maximum recommended hole diameter Results Learnings: Metal Duct construction result increase Core frequencies processors. cables motherboard contribute MHz.
Recommendations
Make Duct from non-conductive material. Performance impacted using plastic Duct. Connect power cable directly power supply, motherboard.
Profile Duct Design Guidelines
Appendix Profile Heat Sink Drawings
Profile Duct Design Guidelines
Profile Duct Design Guidelines
Profile Duct Design Guidelines
Profile Duct Design Guidelines
Profile Duct Design Guidelines
Profile Duct Design Guidelines
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