Best card to run in a x16 slot in x4 mode? No dual 8x on this mobo

So your adaptec x4 card will run at x4 in a x16 slot It's a good sign the x1 card works, but still isnt proof the x4 will work Ideally for

PCIe x4 speed vs x8 speed vs x16 speed Tested with rtx 3060 ti

pcieslot Pci express x16 vs x8 vs x4

pcie2 slot Yes, it works just fine, obviously it's only work at x4 speed I would check whether the x16 slot can handle the power load of the