LENOVO ThinkSystem SR550 / SR650 (x16/x8)/(x16/x16) PCIe FH Riser 2 Kit
"Riser Card 2 option for ThinkSystem SR550 which provides PCIe slots 5-6
- Slot 5: PCIe 3.0 x16; full-height, half-length
- Slot 6: PCIe 3.0 x8 (x16 mechanical); full-height, half-length
NOTE:Requires 2nd CPU to enable PCIe Slots on Riser"