Got some S19pro 100th units set up yesterday and everything fired up perfect.  Today I notice one board on one unit isn't hashing at full rate.  A half dozen reboots and a factory reset hasn't fixed the problem.  Airflow is good, temps are good, and I replaced the Ethernet cable to be safe.
   Each board should run 34th.  Board #1 fires up just like the others and goes to 34th.  Then, over the next several minutes, it's will slowly drop to about 24th and sit there.

The error I see in the log is this:

2021-10-30 18:14:39 Init done!
2021-10-30 18:14:39 STATUS_OKAY
2021-10-30 18:14:39 start the cached job
2021-10-30 18:14:39 Version num 65536
2021-10-30 18:14:39 Mask num 0x1fffe000
2021-10-30 18:14:39 opt_multi_version = 65536, interval timeout = 2945120
2021-10-30 18:14:39 freq = 525, percent = 90, hcn = 4993, timeout = 2945120
2021-10-30 18:14:39 set_start_time_point total_tv_start_sys=176 total_tv_end_sys=177
2021-10-30 18:14:39 set_voltage_by_steps to 1350.
2021-10-30 18:15:38 set_voltage_by_steps to 1340.
2021-10-30 18:15:40 set_voltage_by_steps to 1330.
2021-10-30 18:15:42 set_voltage_by_steps to 1320.
2021-10-30 18:15:56 !!! nonce crc error
2021-10-30 18:15:58 !!! nonce crc error
2021-10-30 18:16:00 !!! nonce crc error
2021-10-30 18:16:02 !!! reg crc error
2021-10-30 18:16:03 !!! nonce crc error
2021-10-30 18:16:03 !!! nonce crc error
2021-10-30 18:16:03 !!! nonce crc error
2021-10-30 18:16:06 !!! nonce crc error
2021-10-30 18:16:06 !!! nonce crc error
2021-10-30 18:16:15 !!! nonce crc error
2021-10-30 18:16:18 !!! nonce crc error
2021-10-30 18:16:20 !!! nonce crc error
2021-10-30 18:16:25 !!! nonce crc error
2021-10-30 18:16:27 !!! nonce crc error
2021-10-30 18:16:28 !!! nonce crc error
2021-10-30 18:16:39 !!! nonce crc error
2021-10-30 18:16:43 !!! nonce crc error
2021-10-30 18:16:45 !!! nonce crc error
2021-10-30 18:16:53 !!! nonce crc error
2021-10-30 18:17:02 !!! nonce crc error
2021-10-30 18:17:09 !!! reg crc error
2021-10-30 18:17:10 !!! nonce crc error
2021-10-30 18:17:11 !!! nonce crc error
2021-10-30 18:17:20 !!! nonce crc error
2021-10-30 18:17:30 !!! nonce crc error
2021-10-30 18:17:43 !!! nonce crc error

Any ideas?   Loose connection somewhere?