Whats the difference between a D0 and C0 overclock?

I am still confused that someone that can surf the Internet can't pull up GOOGLE and do homework on their own!

Your 2 minutes on google didn't answer his question though.

D0 can do 4.5GHz on air if you know what you're doing, maybe higher.

C0 4.0 air, D0 4.5 air. MAybe/Maybe still depends, luck of the draw. Since you still dont know the difference, you probably arent smart enough to get either one to 4.0+