UCP 700 W (also known as RS700-AAAAA3-US) from Cooler Master uses a DC-DC converter on its secondary, i.e. it is basically a +12 V power supply using two small power supplies to convert the main +12 V output into +5 V and +3.3 V. This is the same principle behind power supplies from Antec Signature, Seasonic M12D, Corsair HX (750W and up) series and at least with these other units it proved to deliver very high efficiency. UCP 700 W is 80 Plus Silver certified, meaning that it provides at least 85% efficiency at full load and at least 88% efficiency during typical (50% load) operation. By the way, UCP stands for Ultimate Circuit Protection.



Link: Hardware Secrets