AMD 30925 manual Processor Heatsink Grounding

30925 Rev. 3.04 February 2004	Builder’s Guide for AMD Opteron™ Processor-
	Based Servers and Workstations
8. Processor Heatsink Grounding

Although grounding of the processor heatsink has not yet been required on any AMD Opteron processor-based systems, grounding of the processor heat sink can further lower the harmonic EMI levels of the processor. Many AMD Opteron processor-based motherboards contain grounding pads around the footprint area of the processor. These grounding pads can be used to ground the heatsink to the motherboard.

If excessive system level EMI radiated emissions exist after attempting all the listed EMI reduction techniques, then more extensive remedies may be necessary. First, determine if the emissions emanate from the system I/O cables (including the AC power cord) or from aperture leaks in the system chassis. If EMI emissions emanate from a particular I/O cable, then improved filtering or cable shielding may be required on that cable. If EMI emissions emanate from slots or seams in the chassis enclosure, use copper tape across the apertures to improve shielding effectiveness. If copper tape reduces emission levels to a satisfactory level, then chassis sheet metal changes or conductive EMI gasketing can be added at that location.

Chapter 6 EMI Reduction Techniques 45