I sometimes use a gaussmeter to measure the magnetic fields around my computer, keyboard, mouse, and headphones (all wired directly into the computer).
The strange thing is that in some houses I've lived, there's virtually no magnetic field at all, while in other houses, there's an extremely high magnetic field around all my peripherals (even though the hardware never changes). Some houses just seem to have really high magnetic fields everywhere, while others don't.
Does anyone know what causes these strong fields, and is there anything I can do to keep them out of my computer? I don't want unnecessary magnetic fields engulfing all my hard drives (or my body, for that matter).