1. The depreciation cost of new hardware made this economically a no go. With second hand hardware, there was some number fiddling you could do to make it kind of work until it required any kind of human intervention whatsoever, then the labor costs dwarf the savings.
2. Computer enclosures are not designed to minimize the db/W/$. Low noise computers are generally achieved by reducing the power of parts and using expensive materials. High wattage computers tend to be extremely noisy. We couldn't be having a noisy heating system in our workplace, distracting everybody.