said by Chrno:
Turbo is the only way you can overclock these processors. You can not sustain a constant 4.5GHz clock during idle. When you adjust the CPU multiplier in your BIOS settings, you are basically adjusting the maximum turbo multiplier.
It might depend on what motherboard you're running. With the OP's MSI, I'm not sure. My Gigabyte board on the other hand, there's a few different ways you can overclock. I would think both boards are nearly the same though.
You can disable Turbo Boost completely and then adjust the clock ratios from there. Which in turn will give you a 24/7 overclock.
Or, you can simply adjust the Turbo Ratios settings for an overclock only when under load.