Perhaps use open-ended PCIe x1 slots instead of PCIe x16 slots? #9

PCIe X1 to X16 Slot Extension Adapter Add-on Cards & Peripherals pcie x1 in x16 slot For example, an x1 slot can have only one transfer lane used by the x1 card inserted into the slot; x2, x4, x8, and x16 slots are also available pcie x32 slot However, PCIe x1 cards can be installed into all PCIe expansion slots, including x4, x8, and x16 PCIe slots Often people underestimate their

pcie 4 nvme in pcie 3 slot PCIe to PCI Adapter Card expands two PCI slot via your motherboard with PCI Express slot · with PCI Express Specification ·