Precision 7920 rear flex bay installation - which cables needed

Hi have a precision 7920, which came installed from factory with a CD drive at the front, and HDD flexbay also on the front, composed of two PCIE craddles and two SATA cradles. I ran out of HDD space on this front flexbay, and after some struggling with DELL support, got new flexbay craddles for the rear (module 575-BBSI, to connect to the integrated Intel controller).

Installation went mostly fine, but at the end I seem to have no place to connect the SATA and power cable for the rear flexbay. I only see two SATA plugs at the bottom of the circuit board, which are taken by the CD drive and the HDD slots on the front flexbay. The PCIE slots of the front flexbay, are connected to PCIE slots at the top of the circuit board. Near those, there are two free slots that are similar in shape to the SATA slots, but marked as PCIE as well.

There is no free power plug that I can connect to that I can see.

So it seems that, at the moment I have no way to connect the HDD cable from that rear flexbay in my system (I can connect the fans and temp sensors fine). Any ideas on what I might be missing to get this installed correctly? Dell support in my country is rather poor with this issue, so if anyone out there can help, that would be great.