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EMI (Electromagnetic Interference)

EMI (electromagnetic interference, sometimes called EMR, for electromagnetic radiation) is noise caused by electrical devices. Many devices can cause EMI, such as a computer, a pencil sharpener, a motor, a vacuum cleaner, an air conditioner, and fluorescent lighting. The electrical devices around the computer case, including a CRT-type monitor and speakers, cause more problems than the computer.

A specific type of electromagnetic interference that affects computers is RFI (radio frequency interference). RFI is simply those noises that occur in the radio frequency range. Anytime a computer has an intermittent problem, check the surrounding devices for the source of that problem. For example, if the computer goes down only when the pencil sharpener operates or when using the optical drive, EMI could be to blame. EMI problems are very hard to track to the source. Any electronic device including computers and printers can be a source of EMI/RFI. EMI/RFI can affect any electronic circuit. EMI can also come through power lines. Move the computer to a different wall outlet or to a totally different circuit to determine if the power outlet is the problem source. EMI can also affect files on a hard drive.

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