BIOS update history (according to Supermicro support):

1.1b

  1. Fix a FAN control malfunction problem after AC loss.
  2. Enable workstation, quiet, super quiet fan control mode for 4-pin fan only for revision 3.1 board.
  3. Change revision to 1.1b.
  4. Pass BIOS CHECK 4.0.0

1.1c

  1. Change FAN control by using FANOUT1 and FANOU2 instead of FANOUT2 and FANOUT3 according to hardware
  2. Change revision to 1.1C