Looks like chain[2] was originally from a different miner. That voltage is the setting in the eeprom on the hashboard. The miner will not operate if the 3 hashboards don't have the same voltage setting. So you'll either need to buy a programmer to burn the eeprom with compatible settings or use aftermarket firmware.
Thank you so much for helping me again. You are absolutely correct. I bought this miner 2nd hand and it came with bosminer. It ran fine for few months. When it started to give trouble I switched to stock firmware to troubleshoot. I believe eeprom has a finite reprogramming life. May be the previous owner has already exhausted that. So he was using bosminer to get away with it. It is also possible that I misplaced this 3rd board from another s17+ miner while cleaning or trouble shooting.
Setting in this miner is 1920, 1920 and 1960 with 1960 being kicked out.
In another s17+ cards are running with stock firmware with voltages 1940 & 1960. So it looks like a difference of 40 is unacceptable but a difference of 20 is acceptable. I am thinking if I exchange this board with the one having 1940 in the other board then may be it will run with 1960 there and may be the board with 1940 will be acceptable in this s17+ where others boards are at 1920. I will do that and report back after the day job. I am also thinking about tring vniche and awesome miner if they are better at troubleshooting. While bosminer works fine for running them efficiently it is not good for trouble shooting or I am not good enough to trouble shoot with bosminer.
Really appreciate your insight and guidance wndsnb!