DL360 Gen10 PCIE Slot 3 not PCIE Compatible?

An x4 PCIe device has a theoretical max transfer rate of MBsec according to wiki

PCIe x16 5 x PCIe x16 4 x PCIe x16 3 x PCIe x16 Power Phase, Chipset, Memory, Slots, Multi-GPU, Graphics, Audio, Network

pciex1 slot While PCIe is compatible with older generation cards, the older cards will not be able to access the full bandwidth of PCIe As an

pcie x1 slot function 3 Slot x16 Gen4 PCI Express Backplane Dolphin's IBP-G4X16-3 three slot backplane enables customers to establish a remote access to two PCIe devices