That's one weird question !! no seriously i won't agree cause just a few meters away from me lies a Dell Optiplex GX100 ,this one : http://images.google.sc/images?hl=en&q=dell+optiplex+gx100&btnG=Search+Images&gbv=2
and it works swiftly, not a single noise. You wouldn't even know if its on.
Ok maybe the noises are the fans or maybe dust and all that.Or maybe things a are getting a bit rusty.