Amazon.com: ADT-LINK PCIe X8 to X8 Adapter Cable for Graphics Video Card PCI Express Extender PCIe X8 to PCIe X8 Slot Extension Cable for 1U 2U Server (80CM) : Electronics
Expansion Backplane, 8 PCIe x8 5.0 slots (581) - One Stop Systems
PCI Express x8 to x16 Riser Card Male to Female Graphics Card Riser PCIE 3.0 PCI-E 16x Ribbon Extension Cable with Magnetic Base - AliExpress