Normally the AC ground tip that causes the noise in your systems as it creates circulating ground current in the circuits. Get an AC adapter with no ground plug or take you're Plyers and remove the command ground end of the connector.
Connecting all the chassis to ground will lead to and increase to noise besides most new components don't have a chassis ground connector, those days have passed. The connect all the chassis grounds is to a star from each chassis. So each components will have a sperate ground run to bus bar or star point. When connecting an earth ground the rod must be buried 6 to 10 feet. There is a piece of gear that will measure when the ground is at earth potential, it's called a Megger. Different soil types make a different where there is earth potential.
On Telecom systems the chassis ground or connect to a large copper bar normally 16 to 12 AWG. This ground needs to be a very low impedance or it may cause noise. Of course the main purpose is from voltage surge and Lighting strike. The ground systems can fail to protect with out other protection devices.
Jim
