Can anyone explain why over the years, the GHz speed has decreased? My early '08 Mac Pro is an octocore 3.2GHz machine. Why are the 2010 models 2.66/2.96 GHz at the high end? I'm sure the 2010 models (and soon to be 2012 models) are much faster -- I just don't understand why the speed went down. From a marketing standpoint, isn't that underwhelming?