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#21
The secondary cores will kick in automatically once you have a good load on the cpu itself. Generally unlocking a cpu is mainly overclocking it!
I didn't go directly to Antec to see if there any higher wattage model in that series but knew it wouldn't be likely being their lower line. The TPs are their higher powered series going upto 850w. For the most part however you want to see just what your total requirements will be as well as picking out one with good amps seen on the rails and known as a stable brand to see one with good regulation.
When creating a new array you need two or more identical drives depending on the type of array to start with. Just because you have two or more drives installed doesn't mean "You Must Have" an array! Whoever told you that is way off base!
The most widely used purpose at this time for arrays in general is typically server or storage. But they can be fragile in the home user situation as well. One reason I run two storage drives is for backing up one with the other in part as well as some difference in the files being stored between them.
As for using different makes or even different model series by the same manufacturer that would never be advised for any array being planned. Having different makes and models as individuals however shouldn't make any difference except for having a good supply to cover the extras you install.