Ah, ok.
Each diode runs at a nominal 3 volts. It depends on the current, so it can draw as little as 2.5 . Anyway, the voltage of the board depends on how many diodes are wired in series. For example, the 288 boards are wired 16 in series x 18 in parallel (actually two 8x18s), so they run at 48 volts (or less). The 312 board appears to be wired 12 in series x 26 parallel, so it runs at 36 volts. And the 304 board is wired 38 in series x 8 parallel = 114 volts. The big boards get a little hot, so the voltage goes up a tad.
If you look at the board you can see the pattern. Basically it doesn't make a difference in performance. Either 36 or 48 volts will give you enough flexibility in drivers. I'd stay away from the 304 board.
Each diode runs at a nominal 3 volts. It depends on the current, so it can draw as little as 2.5 . Anyway, the voltage of the board depends on how many diodes are wired in series. For example, the 288 boards are wired 16 in series x 18 in parallel (actually two 8x18s), so they run at 48 volts (or less). The 312 board appears to be wired 12 in series x 26 parallel, so it runs at 36 volts. And the 304 board is wired 38 in series x 8 parallel = 114 volts. The big boards get a little hot, so the voltage goes up a tad.
If you look at the board you can see the pattern. Basically it doesn't make a difference in performance. Either 36 or 48 volts will give you enough flexibility in drivers. I'd stay away from the 304 board.