You can use new S5 Hash PCB ( 18 pin connector) with S5 Control PCB (16 pin connectors) Need only a 16 pin cable.
But what if I have S5 control PCB (18 pin connectors) and S5 hashing blades (16 pin connectors and 16 pin cables)? Can I use them together and if yes - than how?.. Bitmain was not able to give me an answer...