This morning I was reading an article that claims best in class UPS can be as efficient as DC power. This is the UPS “eco mode” thing again. Yes, an AC UPS can be efficient if you run the load directly from the commercial AC, bypassing the batteries and inverter, you might as well be plugging the load right into the outlet. Of course you loose power quality protection and introduce power burps in switching the load to battery (there’s a reason manufacturers abandoned standby UPS many years ago). There’s just no way AC-battery-inverter-AC power supply-DC to the motherboard is ever going to come close to AC-DC-DC to the motherboard.
Vern, SwiftWater Telecom