This just doesn't make much sense to me. How is it more efficient to convert 400vdc to 12 and 5 than to convert 400vac? They both will involve a switching power supply. In real life the "computer" itself runs on 1.5 to 3v anyway. The disk drives are still 5 and 12. When I was doing physical planning the RAMAC racks were the most "power dense" box in the room. They are basically a rack, stuffed with 3.5" hard drives.
