While not a full answer to what you are looking for it may help you to work out whats required for the drives your interested in using
http://extreme.outervision.com/psucalculatorlite.jspOne power supply may not be the same as another at the same wattage more so if its a generic no name brand for OEM use etc, although the label on it should provide you with a break down of the available wattage per voltage that the supply will output.
