I am pretty sure it has nothing to do with the soldering. My Die 0 DC/DC low board becomes a perfectly working board when I simply unplug the other 3 boards in the system. KnC support suggested I try rearranging the ribbon cables on the controller board to see if the problem follows. I have not tried yet, but will attempt this tonight. Both KnC and Bitcoinorama have confirmed that these dead die issues are almost all not physical hardware issues and more about power distribution and firmware.