Thanks it's still syncing so should be OK.
One more thing. I notice when I select System - Shutdown from the UI menu on web browser that it shuts down the node and the miner but the fans on the Apollo II are spinning at full speed and for some reason do not spin down. The system doesn't halt so I have to manually switch the box off.
Is this a known bug or any idea how to fix?
This is normal operation. Once the controller shuts down the fan goes high speed on default. Its a hardwire pull up on the fan PWM as a safety measure (ie all if controller fails, then onboard temp sensor power kill switch fails, as a backup of the backup the fan would go high speed).
It's also an indicator that the unit is safe to shut off, since when you shutdown in menu it takes a while for the controller and node to safely save the state of the blockchain and shutdown.