In my efforts to run my servers as efficiently as possible, I started using twelve volt power supplies with some smaller machines which consumed sixty watts or less. It made a big difference! Even with high quality normal computer power supplies, the difference was at least ten watts.
Little did I know that there is another advantage to those higher quality power supplies: they don’t fail as often. In the two years I’ve been using twelve volt power supplies, I’ve had four of five fail me - and that’s not out of hundreds of power supplies - its from two or three running power supplies.
I still have a few machines running on these types of “power adapters”, but I’m trying to phase them out as quickly as I can.