Well, I am at a loss of whats going on with my setup.
Got replacement card and the rig been mining about 12 hours.
Now I get notification of hashrate drop. I login to see a few of the cards at Zero.
Reboot Pi and only first 3 cards are hashing.
My room is at a constant 60F with fans blowing over the cards.

Set all chip speeds to something slow like 50 with autotune off, and restart chainmminer. If the problem persists, reseat the cards.
Just got to work and shut the miner off.
I moved it and realigned the fans etc...to be sure that none of the cards are vibrating.
All the boards started up...
Guess I'll have to keep a close eye on them and have my laser digital thermometer at the ready.
Now praying for this 1 day 14 hours block to be finally solved. lol