I had this happen overnight as well on one of mine. Temp on mine is 42 & 43 and it is sitting in an aircon server room.
Unit is definitely hashing away on 400 setting (202Gh/s) and pool reporting continual hashing data, so xxxx must be bogus in some way, or at least does not prove unit has stopped.
I will join this club.
Woke this morning to:
xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
Shut it down and let it sit for 5 minutes.
Now back to:
oooooooo oooooooo oooooooo oooooooo
oooooooo oooooooo oooooooo oooooooo
(at least for the moment...)
S1 had been running for >4 days constant.
I do not have them very long but i see them showing those each day, after reboot all seem ok.
but during a day they slowly change all into the x ....
When i reboot them they are back to o, the nasty part is they are only a few days in my posession.
Even changed the psu from 850w corsair to nzxt 1000w and my 1350w one.
Seems to keep coming back, not sure if the fix on the fan will help will see that tommorow.
Crossing fingers that will do the trick