Thanks to Coolbho3000, you can now overclock your Evo to 1.2+GHz. He has posted all of the files necessary for achieving this speed over on his thread at XDA-Developers. Not all Evos are the same so your exact speed may be more or less his achievement of 1.267 GHz. In the video below he also uses Linpack for Android benchmark testing application which can be found in the Android Market or by scanning the QR code at the end of this post.
Enjoy and feel free to leave any comments or questions below.