PCIEX16E-844S | PCIe x16 edge connector to one PCIe x8 and two PCIe x4 Slots riser cable | x16 to x8 and x4 PCIe bifurcation riser cable | PCIEX16E-844S
iStarUSA One PCIe x16 and Two PCIe x8 Riser Card DD-643655-C7
PCIe 3.0 x8 vs. x16: Does It Impact GPU Performance? - YouTube
Can this configuration work on the PCIE slots? : r/pcmasterrace