Not to dig too deeply into failure analysis, but I've found a huge difference between crap quality and good quality PS's. The crap capacitors dry out quicker, and the cheap bronze bearings in the fans (Another big failure point) gum up, dry out, and fail. After disassembling about 50 random failed PS's, Capacitors were the biggest failure, and the fans were often on the verge of failure, if not failed. When it fails, a crap PS can also take out the HD, MB, Memory, and even KB and mouse. I've seen it happen more than once.
On the other hand, I wouldn't trust the most reliable drive in the world. Especially with modern drives, it's not a matter of if, but when.