Perhaps I'm missing something, but that setup does not seem very safe. I have (4) Antminer S1's all overclocked to 393.75 mhz and each Ant uses about 406watts at the wall. The 400mhz setting uses even more power, so even with my conservative power numbers, you're pulling at least 1218 watts out of a 1250w max load PSU. This is a recipe for a disaster.