Think I may have sussed it but I would like your input first.
My PSU has 2 sets of 4 round pin connectors that powers up the internal case fans and at the end of these leads is a small different connector - 1 called P7 the other P11.
Now when I had the board out and got it running I didn't have either connected but all the fans came on.
Now I had the P7 lead plugged into the SYS_Fan connection on the board as I assumed as the 4 pin connectors were attached to the case fans it made sense.
I have now tried it connected to the bare board and it didn't work, so I think I have sussed it.
My PSU has 2 sets of 4 round pin connectors that powers up the internal case fans and at the end of these leads is a small different connector - 1 called P7 the other P11.
Now when I had the board out and got it running I didn't have either connected but all the fans came on.
Now I had the P7 lead plugged into the SYS_Fan connection on the board as I assumed as the 4 pin connectors were attached to the case fans it made sense.
I have now tried it connected to the bare board and it didn't work, so I think I have sussed it.