# More 12-volt Tweaks — Computer Power Supply

I mentioned last time that I wasn’t happy with the efficiency of the 12V power supply I installed for running the lights, water pump, furnace, and a few other smaller items.  How bad was it?  Well, putting out 2 amps at 12.3V, it was drawing 52W from the wall outlet.  That’s less than 50% efficiency, and while it isn’t a lot of power being wasted, I expect this power supply to be on 100% of the time–so in terms of total energy wasted, it would account for a pretty big chunk.  At 5A output, it was a little better, but still needed 100W in (60% efficiency).  Could a computer power supply do a better job?