Nice rig! Now what is it you want to do with it, overclock it to do benchmarking to try get the biggest scores? Because you will see NO difference running @1600. To get it running @2133 I think you need to overclock your system. Do you have XMP enabled?
Cpu @3800 is when Turbo mode kicks in when applications need it , otherwise it will downclock, unless you turn off all the power saving in Bios like EIST etc.