[Help] How to enable other PCIE Slot? Seems slotting other GPU or riser into other slot, device manager not detecting.

I need to use other PCIE slots for other GPU, capture card, another M.2 adapter etc. Please let me know how to enable PCI slot 2,3,4. Even relocating the stock GPU into below slot the system not posting to a display. How? Bios Settings? Mods?

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Model : Aurora R12 RTX3080 i9 11900 16GB DDR4