Have you noticed any 10 or 15 Ghz CPUs? Most manufacturers have redesigned their chips to do more per clock cycle because it is expensive and complicated to make them run at higher clock speeds. This is also why multi-core CPU's are the rage. They can boast about higher preformance without having to break the laws of physics.
Just as a note, bandwidth = spectrum. I spent 10 years working in the radio/communications arena and there really isn't any way to get around the more data you send across the wire the more spectrum is used.
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