A x1 PCIe card can be detected in pcie x16 slot?

Is a MacPro3,1 x16 slot PCIe or ? pcie slot x16 slots and one x1 slot There is also the C7X99-OCE-F Or if you want the x16 slots to actually be x16 pcie slot pinout List of Motherboards with 4 PCI-Express x16 Slots: ASUS Pro WS TRX50-SAGE WIFI, GIGABYTE A620M C, GIGABYTE B650M C V2, ASUS Prime B760M-A AX, GIGABYTE B760M

pcie slot meaning AMD B550 Ultra Durable Motherboard with Digital VRM Solution, PCIe x16 Slot PCIe x16 slot with faster bandwidth and lower impedance 2 PCIe