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Old 01-25-2014, 08:24 PM
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dave911 dave911 is offline
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Default Re: 1kHz PC & Speaker Noise - HELP!!!

The sound coming from the case sounds like the switching power supply is whining.
The fact that the frequency changes as you change loads also suggests the power supply. Could be the output filter is letting switching noise onto the PC supply bus.
Also have you add a battery backup recently, some of them can introduce switching noise.
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