Basically, if you're getting noise (or RFI) the problem can be anywhere between your computer cord to the fusebox to your outside powerlines. I'd start by checking the connections to everything. Check the cord connected to your pc. Shine a flash light and make sure there's no oxides or dusty material.
Check outlets with a volmeter. Compare your computer outlet to other outlets making sure the power is balanced.
If you have an extension cord, plug the pc into a different breaker. Just to check if the breaker is the problem.
Then check the fusebox. Listen for any noises. Sometimes you'll hear buzzing on bad breakers. This happened in my studio. After I replaced the breaker the problem went away (which was noise, not radio stations).
If you have a 6 strip adapter, try plugging that in to the socket then plug the computer into the adapter. If it's already in a strip remove and connect straight to the wall.
Cheap DC converters are another common culprit. I'm not talking just about the DC power supply in your computer. But ANY old DC converter in ANY room of your home can create pockets of interference. One way to "hunt" down this noise is to turn on an old, portable AM radio. Then walk around your home pointing the antenna at wires, sockets, etc. Also go to the fusebox and you can flip the breakers off. Turn 1 on, touch the antenna to it, turn it off. Turn another on, repeat over and over. If the radio screams with noise / RFI that can be picked up by anything with speakers.
Sometimes the problem is as simple as replacing a wire, a breaker, a DC converter. Other times insulation cracks on powerlines and only the power company can fix it.
At any rate, I'd go play around with an AM radio. You have RFI that's coming from somewhere. If you merely turn down power on devices 1 by 1 many times you can isolate what's causing it. You start with breakers then if that doesn't work you go around the house unplugging everything. And when you start this, always start with old DC wal warts. Like the DC converters that look like little cubes. If none of this works then get a pro on it.
ps. Left out 1 important point. Many times your neighbors shitty DC converters & devices can interfere with your own. In which case it's unlikely to stop. And you're gonna need to insulate. Or you can reflect / amplify a large field of RFI back towards their home, let them deal with interference for a few months and maybe they'll toss / replace whatever shitty device they own that's causing it.