Wide-load Efficiency
The 80 PLUS certification is an indirect way of ascertaining PSU efficiency. 80 PLUS Bronze demands at least 85 percent efficiency across a 20-100 percent load. That's met rather easily by the EVGA. In fact, our Chroma-derived numbers suggest that EVGA could just about label this an 80 PLUS Silver. The 550 B5 is therefore sits at the very upper echelons of its stated efficiency.
Compare that with the 80 PLUS Gold from Corsair. There's not much in it, especially as we are comparing two different capacities. The EVGA needs a watt or two extra at the wall to deliver the same amount of juice to the components.