Onboard connectors + 8i RAID adapter
The following shows the cable connections for the 16 x 2.5-inch SAS/SATA configuration with one 8i RAID 
adapter.
From To
Backplane 1: SAS Onboard: SATA 0, SATA 1
Backplane 2: SAS 8i RAID/HBA adapter on PCIe slot 2:
•  Gen 3: C0C1
•  Gen 4: C0
Connections between connectors: 
1  ↔  1 ,  2  ↔  2 ,  3  ↔  3 , ...  n  ↔  n
Figure 38. Cable routing for the 16 x 2.5-inch SAS/SATA configuration with one 8i RAID adapter
Chapter 3. Internal cable routing 93