The power supply does have a daughter board. This board supports an 8 pin cable that splits off into 2x 6 pin connections.

Power supply extended card part number is M6NP2:

 

It goes here ( this is a picture with the power supply removed ):


6 PIN splitter cable part number D92C9:

Precision 5810 power supply part numbers:

YFY1V - 425W PSU

VDY4N - 685W PSU

RHHKV - 825W PSU