Lenovo ThinkSystem SR650 V2 Maintenance Manual page 116

Rear backplane: 4 x 2.5-inch SAS/SATA
To connect the front backplanes, refer to "Front backplanes: 24 x 2.5-inch SAS/SATA" on page 105.
The following shows the cable connections for the 4 x 2.5-inch SAS/SATA rear backplane if installed.
From
Backplane 4: SAS
Backplane 4: PWR
Connections between connectors:
Figure 50. Cable routing for the 4 x 2.5-inch SAS/SATA rear backplane
ThinkSystem SR650 V2Maintenance Manual
106
To
CFF expander: C3
Riser 1: PWR1, PWR2
↔ ↔ ↔
, , , ...
1 1 2 2 3 3
↔
n n