no i mean the ground cable of the computer,
it happens sometimes that electricity goes through the ground cable
and genrates a buzz when connected to external amplifiers.
if this is what happens you can solve the problem disconnecting the
ground of the power socket of the computer. there are also "ground loop isolators" that can fix this without disconnecting the ground cable, you can google around to find more information. but i'm not 100% sure that is what happens with your computer....