You'll have to make a Turbo Profile in AMD Overdrive.
There's 2 stages to Turbo
1 - Will Run at 4.1Ghz if it has enough headroom under load.
2 - Will Run at 4.2Ghz using 4 threads if it has the headroom (4 threads active, 4 threads inactive)
In AMD Overdrive you will have to adjust stage 1 Turbo to run at 4.6Ghz, and then make sure you have the voltage high enough.
But it would probably still be easier to overclock it to 4.6Ghz with Turbo Disabled, and leave the power saving options on, so it drops way down when idle.