Hello, Various Question of Asus WS X299 Pro/Se:

1 - Conector U.2: The U.2 connector, according to the manual, says that it is shared with the M2.2 socket (the second unit), to this connector without putting any M2 SSD, you could connect a Mini SAS cable (SFF-8643 to 4 Satas) and work by servicing 4 SATA hard drives without RAID?.

2 - Power supply: I intend to buy the Corsair HX1200i, this PSU. It has a cable and the possibility of connecting to the motherboard for the control of the PSU itself, now I do not know if this one with its cables is compatible with the connector that the PSUSMB1 motherboard has, or if I have to buy another compatible cable, or not. It is compatible and use the alternative cable that has the PSU that is by USB.