There's not a chance in hell you would get 6 cards to run reliably on a cx750. They have issues when pushed hard.
4 rx580s/570s is about all you want to do on a cx750. PSUs are more efficient at ~50-80% than at full load.
I thought 6 would be pushing it. So when someone says a 1200watt is over kill for a 6 card rig 1070 and rx480, would you agree? I do have a question about hashrates and maybe if it is related to what I am seeing on nanopools stat site. Do you have spikes in you hashrate or should it be relatively flat line?