I tried it with a different power supply and got the same results without the smoke. So I guess I'll RMA the board back to ASRock. Oh so not happy to do this again.
You can try that, but don't be surprised if they refuse it. Essentially it was your PSU that likely damaged the board, it wasn't some sort of defect with the board, so ASRock may well decide that you'll have to pay for a replacement.