Sounds like a dead PSU to me. Your A741 could have been trying to pull more than what your Corsair PSU could handle. That may also explain why your A741 has been so temperamental thus far — I'm guessing that your A741's left board has much higher power requirements than its right board.

It'd be best to grab a server-grade PSU kit going forward. They're able to perform much closer to their rated specifications than conventional PSUs, generally have much better efficiency, and are more likely to be able to handle the A741's spikes in power draw. They're also better able to run continuously under heavy load; conventional PSUs are generally not designed for sustained, continuous use.