Will PCIe x1 x4 cards work in x16 slot?

In ASUS 「PCIe x16 Slots - 2」

Will PCIe x1 x4 cards work in x16 slot? Enhance your PCB mounting with our 5Pcs PCI Express 16x Slot PCIe x16 164 Pin Sokcet Straddle Mount PCB Slide Lock Female Straight Through Holes Pitch

In ASUS 「PCIe x16 Slots - 2」

mc4 slot 16 PCIe lanes, and they require the full PCIe x16 slot to be fully functional Ethernet Network Cards While most motherboards

according to your own link it could sit in either the top slot or the 2nd slot both the same Multi-GPU CFX support 2 x PCIe x 16 (supports

16x pcie slot if the slot is open like that, you should be good to go if it's not open, you could a) use another riser to adapt the x8 to x16, or b)

You can install PCI Express slots in larger slots but not smaller ones For example, you can install a PCI Express x1 adapter into an x16 slot (but will still