Lenovo THINKSERVER 3821 - Manual (Page 175)

The following illustration shows the internal SAS power and signal cable routing
from the hard disk drives to the connectors on the system board.
1 SAS power cable connector B
2 SAS power cable connector A
The following illustration shows the internal SATA and power cable routing and the
connectors from the DVD drive to the system board.
Chapter 7. Installing optional devices and replacing customer replaceable units 167