Filter
Top Products
30925 Rev. 3.04 February 2004
Builder’s Guide for AMD Opteron™ Processor-
Based Servers and Workstations
Chapter 6
EMI Reduction Techniques 45
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.