That's because the overclocking ability of a non K Intel is limited. You can only overclock a non K to the max turbo frequency for all the cores. Thus you can only overclock from 3.2 to 3.4. That's it bud. No more. If you wanted to overclock more, you would need an Intel k.
For what purpose do you want to overclock? The performance increase margins are pretty small in most gaming situations.