The voltage setting stored in the eeproms (for the current mode if a s17) needs to be the same on all hashboards in a miner for stock firmware to work. If you have logs from the miners with the boards you want to mix, you can tell in advance if they will work together. You just need to find the following section in the logs and check that the voltage setting is the same in the two miners you want to mix and match boards from/to.
022-05-17 22:44:27 uart.c:71:set_baud: set fpga_baud to 115200
2022-05-17 22:44:38 driver-btm-api.c:915:check_asic_number_with_power_on: Chain[0]: find 48 asic, times 0
2022-05-17 22:44:49 driver-btm-api.c:915:check_asic_number_with_power_on: Chain[1]: find 48 asic, times 0
2022-05-17 22:45:00 driver-btm-api.c:915:check_asic_number_with_power_on: Chain[2]: find 48 asic, times 0
2022-05-17 22:45:05 driver-btm-api.c:345:set_order_clock: chain[0]: set order clock, stragegy 3
2022-05-17 22:45:05 driver-btm-api.c:345:set_order_clock: chain[1]: set order clock, stragegy 3
2022-05-17 22:45:05 driver-btm-api.c:345:set_order_clock: chain[2]: set order clock, stragegy 3
2022-05-17 22:45:05 driver-hash-chip.c:502:set_clock_delay_control: core_data = 0x34
2022-05-17 22:45:05 uart.c:71:set_baud: set fpga_baud to 3000000
2022-05-17 22:45:05 driver-btm-api.c:1574:check_clock_counter: freq 50 clock_counter_limit 6
2022-05-17 22:45:07 uart.c:71:set_baud: set fpga_baud to 115200
2022-05-17 22:45:07 voltage[0] = 1780
2022-05-17 22:45:07 voltage[1] = 1780
2022-05-17 22:45:07 voltage[2] = 1780
2022-05-17 22:45:07 power_api.c:219:set_working_voltage_raw: working_voltage_raw = 1780