I have a fairly good sized farm here. I had everything wired up properly on my end for all my miners and was having a similar problem with a new batch I ordered. Was bashing my head against the wall for over a month going back and fourth with parts and RMA. When i got them back I had the same problem as before...

Long story short, it turned out I was just crossing the threshold of what the cities powerline/transformer could provide. It might be worth looking into.