Keep in mind you might have the cpu clock dynamically stepping down it's clock speed based on load. Verify that you speed is
really 1.2GHz by checking the speed in the bios. If it
is 2.0 GHz in the bios it's the OS that is slowing your clock speed down. Try putting the cpu under load and reading your clock speed. Try getting
cpuburn from your distro's repository or downloading it from
http://pages.sbcglobal.net/redelm/ to put your cpu under load and
then look at your /proc/cpuinfo and it should be 2.0GHz