Only two supplies are required for load-balancing. Any number of supplies can be tied together so long as SHR, 12V and GND are all common. Pictured is how we connect three boards for single-point control, with enough power to handle 5 overclocked AntMiner S1 units.
Heavy-gauge 12V common bus (Required)Required for load-balancing, as the load must be common to all supplies.
Heavy-gauge GND common bus (Required)Required for load-balancing, for common return-current path.
Common Current-Share line (Required)Required for load-balancing; the supplies use this line to cross-regulate voltages.
POK1 to EON2 and EON3 (Optional)If boards 2 and 3 are set to external-on (switch 3), board 1's toggle will turn all 3 boards on together.
FAN1 to FAN2 to FAN3 (Optional)If board 1 is set to internal fan AND external fan (switches 1 and 2), the fan signal will backfeed out the external fan pin. If boards 2 and 3 are set to external fan ONLY (switch 2), Board 1's fan signal will control their fans as well. This works best when all 3 supplies are the same model/revision.