I'd run these computers on 240V ... through a single phase 208/240V UPS ... unless they are spam engines, in which case I'd give them a dose of 13800V.
I agree, do check to see if it is spam servers, and maybe let a few power cords/Ethernet cords go missing, or even pop open a network switch or 2 and hit them with a 1 1/2 paddle bit to the circuit board
