Lenovo ThinkStation P500 Configuration Manual page 39

Description of Commonly Used Storage Hardware in P-Series
ThinkStations
Blind Connect Assembly (BCA)
BCA-P : Blind Connect Assembly consisting of two 8639-SFF ports (supporting PCIe, SAS, or SATA drives)
and two 8482-SFF ports (supporting SAS or SATA drives). The assembly also consists of the following
cable connections:

One 4-pin power connector that connect to the motherboard

Two mini-SAS HD connectors that connect to the Multi-IO FLEX adapter (for PCIe
connections) labeled "P1" and "P2"

One mini-SAS HD connector that connect to either the onboard controller or Avago
controller labeled "S/X"

LED lights light up next to each port to show which ports on the BCA are available
when either the Avago or Intel onboard controller is used.

The Avago controller supports all the given ports on the BCA.

The onboard Intel controller supports only two of the given ports on the BCA.