
Don't recall ever seeing "ground loop" mentioned . .
. . in regard to computers, though it certainly is in audio stuff, where a signal can still be "significant" at a very tiny % of the main signal.
Many older boards were, however, essentially "single ground point" with one screw up near the power connection and everything else supported by plastic standoffs. The three 200-MHz and 233-MHz AMD K6 boards I just stripped out of computers one of my clients made me haul away are like that.
Current motherboard thinking seems to be "ground plane" with as much sheet within the board as possible and 7 to 9 ground to chasis points. Plastic motherboard standoffs are no longer used at all, it's all "bolt to metal" now.
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