https://pubs.lenovo.com/sr860/replacement_pcie_riser_n_adapter
PCIe riser card assembly and adapter replacement | ThinkSystem SR860 | Lenovo Docs
Use this procedure to remove or install the PCIe riser card assembly and the adapters.
pcie riser cardassembly
https://pubs.lenovo.com/sr850-v3/internal_connectors_rear_pcie_riser
PCIe riser card connectors | SR850 V3 | Lenovo Docs
See this section to locate the connectors on the PCIe riser card.
pcie riser cardconnectorslenovodocs