Summary: The LS-550 (New) proved to be a good mainstream 550 W unit, providing a decent efficiency between 84.5% and 85.7% if you pull between 20% and 60% (between 110 W and 330 W) from its labeled wattage. Delivering 80% from its labeled capacity (440 W) efficiency dropped to 82.7%, still a very decent number. At full load (550 W) efficiency dropped to 80.3%, still above the 80% mark.
Ripple and noise were always below the maximum allowed.
Summary: I used the
Kill A Watt P3
to measure system load, which was determined to be around 110W at idle and 200W under load. To generate the load conditions I ran the F@H SMP client, 3DMark and a drive replication process simultaneously. With a 125W TDP processor the CPU was by far the most power hungry of the components. I took voltage measurements using a Fluke multimeter at the power supply connector.