AMD 30925 Disable Unused Clocks, Processor Heatsink Fan Cable Routing, Power Supply Cable Routing

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Builder’s Guide for AMD Opteron™ Processor-Based

30925 Rev. 3.04 February 2004

Servers and Workstations

 

2. Disable Unused Clocks

Clock signals that have no load can have high levels of ringing that can lead to EMI problems. The motherboard BIOS firmware should be programmed to detect and disable unused memory DIMM and PCI clocks.

3. Processor Heatsink Fan Cable Routing

A problem sometimes encountered with the processor heatsink DC fan cable is the large loop formed in its routing to the motherboard connector. Shorten this cable length to reduce the loop area as much as possible.

4. Power Supply Cable Routing

Historically, the system power supply cable has been found to be very susceptible to picking up EMI energy from within the system and coupling into the power supply and then onto the AC power cord. It is best to keep the power supply cable against the metal chassis and as far away from the processor, memory DIMMs, and VRM components as possible. This cable routing should be fixed in place with plastic cable ties.

5. Other Internal Cable Routing

Cable routing inside the system should generally be routed along the metal chassis and away from EMI sources such as the processor heatsink, clock modules, memory DIMMS, VRM components, and high speed VLSI modules. Internal cables that connect to front I/O ports such as USB and Audio are particularly sensitive. The use of a shielded cable or a ferrite core or both over these internal cables can be effective at reducing EMI.

6. Rear I/O Connector Shield

One common problem in many computer systems is poor electrical contact between the metal I/O connector plate and the cut out in the system chassis wall. This problem is usually due to soft metal being used in the I/O connector plate. If the metal does not have good spring characteristics, the finger contacts can be depressed and not make reliable contact. A solution to this is to use a hardened stainless spring steel. Additionally, some designs have an insufficient number of contact points to the I/O connectors and the wall of the system chassis. This is usually most apparent around the keyboard/mouse and USB housings. Each of these connectors should have at least two contacts. As a general rule, there should be a contact point at least every 1 cm to 1.5 cm.

7. Chassis Shielding

All chassis designs have gaps and seams to enable assembly and option installation. From an EMI standpoint, however, some gaps are worse than others. The important dimension of a gap or seam is the longest dimension. If you can slide a piece of paper for several inches along a seam, that seam could cause an EMI problem. Spring fingers or foam EMI gasket can be used to seal these gaps or seams.

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EMI Reduction Techniques

Chapter 6

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Contents Revision Trademarks Contents Servers and Workstations EMI Reduction TechniquesList of Figures AMD Opteron Processor ArchitectureList of Tables Revision History Date Revision DescriptionRevision History AMD Opteron Processor Key Architectural Features AMD64 ArchitectureHyperTransport Technology Other Features of the AMD Opteron ProcessorIntegrated DDR Dram Memory Controller Design Methodology for the VSP Platform Validated Server Program VSPValue Proposition Platform Description Model A2210 1U/2P Rack Server Model A8440 4U/4P Rack Server Not Yet a Member of VSP? Servers and Workstations Validated Server Program VSP AMD Opteron Processor-In-a-Box AMD64 Processor-in-a-BoxServers and Workstations AMD Opteron Processor-In-a-Box Heatsink Installation Heatsink Installation ProcedureBackplate Release Liner Ensure Proper Contact Between Backplate and Motherboard Tightening Down the Retention Frame Pushing Gently Down on the Processor Heatsink Centered Over Processor Pushing Straight Down on the Clip Turning the Cam Lever Installed Heatsink Servers and Workstations Heatsink Installation Hardware Considerations System Enclosures and Chassis SelectionBasic System Enclosure Selection Guidelines Basic Chassis Selection GuidelinesPower Supply Considerations Desirable Airflow-Power Supply with Bottom InletPower Supply Guidelines Server and Workstation Platform Power SuppliesCalculating System Power Consumption Power Worksheet 1-Component PowerPower Worksheet 2-Total Watts Total Watts A = W For Each Voltage LevelThermal Solution AMD Opteron Processor Thermal Solution GuidelinesMemory Guidelines for AMD Opteron Processor- Based Systems AMD Opteron Processor InformationAMD Opteron Processor Series and Model Numbers AMD64AMD Chipset Information AMD-8000 Series ChipsetGraphics and Storage AMD-8131 HyperTransport PCI-XTunnelAMD Opteron Processor Utilities and Updates AMD-8000 Series Chipset DriversBit Operating Systems Linux Drivers for the AMD-8000 Series of Chipset Components Drivers for Linux KernelServers and Workstations Hardware Considerations Spread Spectrum Clocking EMI Reduction TechniquesEMI Emission Standards Disable Unused Clocks Power Supply Cable RoutingRear I/O Connector Shield Processor Heatsink Fan Cable RoutingProcessor Heatsink Grounding Servers and Workstations EMI Reduction Techniques Appendix a AMD Opteron Processor-Based System Build Procedure Builder’s Guide for AMD Opteron Processor Builder’s Guide for AMD Opteron Processor-Based Appendix B FAQs AMD Opteron Processor FAQsWhat is the value proposition of the AMD Opteron processor? Validated Server Program FAQs Where are EMI guidelines for motherboards located?Will these validated servers be available in all regions? Builder’s Guide for AMD Opteron Processor