Turns out the Bitmain E3 (NOT the F3 as reported) is not exactly a big GPU mining killer.
180 Mhash
800 watts
About the the SAME performance as a well-tuned 6 card RX 580/480 based rig, and slightly INFERIOR to a well-tuned 6-card GTX 1070 based rig.
My tuned RX 580 Special Edition GPU mine at 31 MH\s while consuming below 90 Watts
Go by "at the wall" measurements, as nothing on the AMD side reports the power usage of the entire card because AMD's HARDWARE on the card only measures power usage of the GPU itself.
Software like Afterburner and Wattman ALWAYS get the power usage wrong, and UNDERreport it a lot on AMD cards as a result.
It's correct for what it is reporting. As you pointed out, often people are just looking at the power consumption of the GPU, from the output side of the VRM. Power to the input side of the VRM will be ~10% higher, and there is a separate VRM for the RAM. There's usually one or two more power rails as well, but their power consumption is minor compared to the GPU & RAM.