I'm sorry but I need to jump in here.
I've seen a lot of your threads regarding this and while I have not answered some folks I know have given you a lot of advice.
However I have one final piece of advice to give. Power supply cabling is serious business. You can at a minimum damage or destroy your PC components with incorrect cabling. At worst you can do that and burn your house down while you are at it. You are asking basic electronics questions that someone whom is taking on a project like this should be able to answer on their own.
The question you are asking now literally scares me as to what you may do, even given the correct answer. I implore you to reconsider this project and maybe try out some other cheaper electronics projects to learn what you are doing before taking this on.
I say this with the utmost respect for wanting to try something like this on your own, but as I said, I am in fear of the next thread being titled "so I blew up my PSU and set a small fire in my home".