Thank you for the replies. I went ahead and flashed braiins OS onto the old control board so I could change each hashboard settings individually in case the old firmware that was loaded (from 2017) couldn't handle mixed boards. The old boards said version 3.x and the newer one 4.x. All seems to be working fine with this setup. It does seem that the new board runs cooler than the two older ones, so I have had to underclock the old ones to keep all around 90degreesC ( poor temps due to this test unit is in a vented sound reduction box and also inside a small outside room :/)