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 :/)
The middle board usually runs a lot hotter than the two on the sides because the fan's motor kind of blocks the airflow so you might want to place the new board in the middle to give a better cooling for the other two boards, also I think the 90 degrees temp is not too bad given that they sit in a noise reduction box.
Good luck.