Naw it's not the power cords, they're the same plugs you use for a PC's power supply as they're powered speakers, and have individual detachable cords, and both speakers make the noise.
It's the PC for sure, and grounding sounds right.. I thought just by screwing in a power supply to a PC the case was grounded though, not sure.. I'll talk to a pc tech tomorrow and see if there's something I can do.
BV not speakers attached to a monitor, they're reference monitors.. These ones:
