As stated before, we test at low loads of 22.5, 50 and 100 watt, modelled after a real system based on an Intel Core i7 4770K Haswell-processor, a Gigabyte GA-Z87X-UD3H motherboard, two Corsair Vengeance Pro memory modules, an OCZ Vertex 4 SSD and a CPU-cooler. The 22.5 watt test roughly corresponds with the idle-usage of this system, whereas the 50 watt test resembles a situation in which one CPU-core is fully utilized. The 100 watt test is comparable with a situation that requires all of the cores to be at full load.
Something that (of course) stands out is that the 1200 watt models in both the Gold and Platinum-series perform worse at low load when compared with the power supplies with a lower maximum power, while the 1000 watt models perform remarkably well at low load. As the load increases we also find that the efficiency of all power supplies increases, and at 100 watt all of the tested models are more than 85% efficient.