What are you hoping for? If you have to ask, then you haven't probably done it before and if you haven't done it before, your expectations are probably all out of whack with the results you will actually get. The SSD's in RAID0 will gain nothing but hassles and benchmark numbers, but no real-world performance difference. Now the spinner drives might gain some actual performance, but since you have SSD's, there is no real reason to use the spinners in any capacity beyond archival type storage as even in RAID0, they won't be as responsive as the SSD's.