395 at the wall? If that is so, assuming a psu efficiency of 90% it draws 356W @12V from the psu. Since the psu is rated for 1200W@12V 3*356W should be fine on 110V, no?!
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i wouldn't do it, not worth frying your hardware let alone start a fire in your home. go get another psu either atx or server or another apw3++.
remember - this is a cheap chinese designed psu so avoid overstressing it at max capacity running 24/7. A good atx psu from a top tier company like evga will work as long as its gold or platinum rated. 550--600w should be fine for one z9 mini. Another alternative is a HP 750w server power supply (600w @120v - 750w @240v). You will need a breakout board and cables to use these.