Yeah I swapped the PSUs out to working miners which are on different breakers and diagnosed the same result. 

What alerted me to the issue was an internet outage.  All the miners slowed and got cold, then when then internet returned, I noticed a couple of miners not come up to speed.  When I got to site and checked it out I found that the PSUs were showing a red LED.

I tried the PSUs in other miners and found it didn't change.

I am pretty confident they have died a death.