Vi and Vout looks ok, so the PMU is not the problem.

What is your hashrate?
It looks like one or two hashboards are having some kind of problem.

You should open a ticket at Caanan and post the log there.

Update:

What voltage offset are you using? Please try with -1 or even -2.

Please check your temperatures, 42 degress C at input is a lot, maybe it's overheating ! Fans are at 100%, this is not normal.
Temp[42]
    TMax[95]
    Fan[5760]
    FanR[100%]