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Okay, so what's happening is from the fact your USB chipset is not properly isolated from other circuitry on the motherboard, and thus the processor, memory, drive, networking, etc, is all causing electrical interference resulting in that sound. Sometimes you may luck out and find it's only the charging circuitry, so if you unplug your laptop from the wall power, it will stop, but in most cases, it's just a poorly designed motherboard. Some possible fixes for you...
- try a different USB port
- use a USB cable with a ferrite core
- try a powered USB hub
- use a different computer
Unfortunately the cause is not the RB itself.