Yes you should be fine. For example the wd 1tb blue hdd, the spec sheet shows average wattage during read/write to be 6.8w. Well under 10w, just for a point of reference. Drives take some power but very little compared to everything else. That's around the same type of power consumption as a couple of case fans. With a 750w psu and that cpu/gpu, you'd probably be fine adding 4 or 5 more hard drives. Also keep in mind that it would be rare to have all hdd's active at once, one or two may very well be idling most of the time.