You must have the auxiliary 6–pin splitter cable that was shipped with your workstation.
The 6–pin splitter cable might be installed on the 6–pin auxiliary power cable.
Locate the 6–pin auxiliary power supply cable with the connector labeled To GFX Card or Splitter and release the cable from the cable retainer.
If necessary, connect the 6–pin splitter cable to the 6–pin auxiliary power supply cable.
Connect the 6–pin connectors of the splitter cable to the 6–pin connectors on the PCIe2 cards.
Secure the cable in the cable retainer.