AFAIK it's common practice to mount an ATX motherboard to conductive brass standoffs inside the case. There are even metal traces around the screw holes to provide contact between the screws and the motherboard ground-plane.

  1. Are these traces just for the screws or are these traces there to provide a path between the motherboard ground-plane and the case?

  2. What's actually better? Conductive standoffs or insulated standoffs?

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    \$\begingroup\$ It only matters on radiated emissions outside the box as the high layer counts have adequate controlled impedances and ground planes for performance, but there may be exceptions. Most use insulated standoffs now that I have seen. \$\endgroup\$ – Sunnyskyguy EE75 Oct 31 '16 at 23:47
  • \$\begingroup\$ The only standoffs i can find are brass standoffs. \$\endgroup\$ – Marty Nov 1 '16 at 0:09
  • \$\begingroup\$ @Marty Brass standoffs are probably the most common. If you want non-conductive then search for "nylon motherboard standoffs". \$\endgroup\$ – DigitalNinja Nov 1 '16 at 0:17
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    \$\begingroup\$ brass is stronger \$\endgroup\$ – Sunnyskyguy EE75 Nov 1 '16 at 0:27
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    \$\begingroup\$ With the inductance of a standoff vs a square board. the board is lower inductance if both are in parallel then the case has little influence on performance unless an OEM has unique emanation issues then they can enable Spread spectrum jitter on clocks or choose the standoff method that works best for CE/FCC tests \$\endgroup\$ – Sunnyskyguy EE75 Nov 1 '16 at 0:31

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