Lenovo ThinkSystem SR665 V3 User Manual page 311

Riser card 3 power and sideband connection (Gen 4/Gen 5)
The power and sideband connections for x8/x8 PCIe riser card 3 and x16/x16 PCIe riser card 3 are the same.
Figure 281. Riser card 3 power and sideband connection
From
Power connector on the riser card
1
Sideband connector on the riser card
2
To
Riser 3 power connector on the system board
1
assembly
Riser 3 sideband connector on the system board
2
assembly
Chapter 6
.
Internal cable routing
301