ASICs not receiving all nonces
You yourself have stated that your boards are failing to hash.
It looks like some form of system test against the boards is failing.
I know I am being captain obvious here.
chain[6]: some chip cores are not opened FAILED!
Test Patten on chain[6]: FAILED!
Until you can find the point of failure with a volt meter, or replace the failing boards.
You can try tuning the voltage / frequency of the miner to see if this helps stabilize them.