The "16th" pin of VGA and "5th" pin of USB are a shield and should not be used as ground. USB and VGA both have a dedicated grounds. In fact USB spec dictates that the host end only should connect ground to the shield. It does not carry current.

I'm not sure if the same applies here. I'm yet to see the actual pinout defined.
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Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)