First of all there is no need to do it, when your processor gets heavily loaded, the frequency changes to the max automatically, and when it's at low to no load, it changes to 800MHz and drops vcore, to both save on battery and component life of your lappy.
I would recommend you leave it as it is.
If you want it to run at full speed always set power mode to "Always On". if it still doesn't do it, get GCPUID (my sig), hit F9 and set the highest vcore, then highest multi.