While buying components for your PC you should look for one or more of these standards compliance symbols on them.

• FCC (Federal Communications Commission)
  Ensures that the device or component complies with FCC Rules, in most cases, Part 15. This part assures that the operation of the device is subject to the following two conditions: (1) The device may not cause harmful interference, and (2) The device must accept any interference received, including interference that may cause undesired operation.
• Canadian Department of Communications Statement. Ensures that the digital apparatus does not exceed the Class B limits for radio noise emissions from digital apparatus set out in the Radio Interference Regulations of the Canadian Department of Communications.