New to overclocking

Definitely do not go and change to 45 right away. Read the sticky. You want to go in steps and test stability at each step.

Overclocking.. Learn about the Sandy Bridge and how to do just that.

Voltage increases will be required to reach 4.5Ghz but before you even think about doing that; YOU NEED TO READ! Proper rule of thumb here, and I'm not being a butt. Read until you know what every single setting in your BIOS's clocking section does. This way you don't accidentally toss 1.8v into that processor and fry it first try.

Learn about the multipliers, voltages, offset voltages, speed step, power saving, turbo boost, BCLK, Ram timings, XMP profiles, and even the simple stuff like applying thermal paste correctly.

Just because you want 4.5Ghz doesn't mean you can just shoot the stars and reach it. I want you to reach your goal; but you need to work for it. I'm more than happy to answer the questions you'll have; but if you don't understand volting; I don't suggest you try for such a high overclock.