High pitch noise coming from power supply (I think)

iAnorak

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Mar 3, 2007
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Depending on where I am in the room, a high pitch ringing can be heard (sounds weird, I know). If I'm standing in certain places, the noise is incredibly bad - others, not so much. I think it's from my power supply but I'm not exactly sure.

Any ideas how I could go about quieting the sound? I've heard about using compressed air to clean out the power supply, since some noise can be caused by dust and hair.