My housemate's desktop has a noisy power supply

[MadMan]

Well if you ever read those FCC stickers, all they ever say is that 'this device does not cause harmful interference.' Doesn't say no interference.

TBH, I couldn't tell you. Are you sure the noise in on the power lines and not just in the air?

Wouldn't an across-the-line capacitor in the vicinity of the radio fix power line noise?