True. Below 20% of the max. output the efficiency will be no good. But even the 1200W you linked has > 89% at > 400W. :-)
Misunderstanding, we are talking about the same thing. See my edit above.
You are right. I misread "50-70% of the advertised PSU wattage" for "50-70% of the advertised PSU efficiency". Sorry for that.
