Depends what else you run on it; I have three hard drives (two are a RAID 0), a processor upgrade w/fan, an added fan, a USB 2.0 PCI card, a PATA PCI card, 2 gigs of RAM (4X512), a DVD burner, and an added fan on the processor upgrade (wires jammed directly into a spare plug) and my machine runs fine with the stock power supply. I could look up all the power needs for each of those items, but I would say if you're keeping it simple and just running either the RAID itself (are you using is just as a RAID box?) or just OEM processor, couple sticks of RAM, and the motherboard along with the RAID, it should be fine...