trying to overclock so I can run games in dolphin 4.0.2 x64

[mill1rbt2]

what do you think I should change the voltage settings to? what should I do to accomplish a 4.5ghz overclock? i'm not the best overclocker and when I tried to overclock to 4.5ghz in the bios the pc shutdown then reset to 3.5ghz or I had to underclock back to 3.5 because of blue screen's..should I set the voltage up or down? maybe I could go into my bios and then write the setting's down?