It’s not ground hum, more like static every couple of seconds. I would describe it like twisting the connector in the audio jack. I have wiggled and twisted it 100 times and that doesn’t cause the noise. The noise just happens on it own. Also headphones make the same noise but cuts off the whole speaker system. Even USB digital speakers make the same noise. I’m using a Geforce GT 610 and a Geforce GT 710 for video. I have a Bluetooth speaker that has no noise.
IMO it’s either the drivers need to be reinstalled or a compatibility issue or bad card. If reinstall doesn;t fix it you may have a bad card.