just a thought but my knowledge is limited compared to most here.  If you ran three miner off one psu.. what if you had voltage drop which would increase the amperage running thru the miner .. could be this scenario.  http://ask.metafilter.com/244859/Voltage-drop-amperage-increase


"If you have switch mode power supplies (e.g. practically all IT equipment these days) then when the voltage drops they will pull more current to keep up their output. If your voltage sags a bit because of too high a demand then they all pull more current and you're boned."

Best regards
d57heinz