To all having PSU issues/reboot/freeze/shutdown, I suggest keeping the same settings as in Clay V8, but modifying power limit in AB to 80% for each card, see if it happens. If it's stable, also check if hashing speed is lower. I am not at home to try this.
I resetted my underclock and it is still working. Claymore should fix this spiking issue, it's not normal.