How did you calculate those numbers ?

125W per Cryptonight looks like the difference between the card idling but powered in the rig and mining.

What you really need is the diff between no card in the rig and mining.

My Vegas will pull ~30-35W just sitting there doing nothing so the real power usage is ~150-160W per card (@93% efficiency, pull from the wall).  For comparison, by MB, CPU, memory and M2 sata disk pull about 25-30W when idling (!)

Please also specify if your numbers include the power supply efficiency or not (and that efficiency if they do).

I haven't seen real 125W pulled from the wall per card yet, unless you severely undervolt and underclock, but then bye bye 2K h/s