Overclocking a computer isn't the same experience for everyone. It is a LOT of trial and error and knowing just how far you're willing to push your expensive processor.
Adjusting core voltages is always a risk and each processor responds to it differently.
First I would try and see how much of an overclock you can get using stock voltages.
When you start bumping up voltages, you run the risk of turning your processor into a very light paperweight.
I'd read this article in it's entirety before you start touching any settings.
http://www.tomshardware.com/reviews/overclocking-core-i7,2063.html
As I said before though, what works for others might not work for you. Just because they got 4.0Ghz out of theirs with the settings that they listed doesn't mean that you'll be able to do the same. You might be able to get 4.1Ghz out of it, you might end up only getting to 3.8Ghz before your system becomes unstable.
I suggest doing a LOT of research before you start touching anything.
When I overclocked my CPU it took me about four days of trial and testing before I was satisfied with my overclock. Also, just because the computer boots up doesn't mean it'll be stable when running.
Prime95 is going to be your best friend. Most people accept 8 hours of Prime95 as being completely stable.
Another good site that has lots of good information:
http://www.overclock.net/