Can I be 100% certain that a PCIe x4 card will fit in a PCIe x16 slot?

Can I be 100% certain that a PCIe x4 card will fit in a PCIe x16 slot? can i put pcie x4 in x16 slot PCIe x16 slot with faster bandwidth and lower impedance 2 PCIe Slot PCIe x4 slot with Lower impedance can maintain its performance candy pop slot The thing is, only one of the PCIe slot is x16, the other one is x4 I have a Radeon RX 580 on the x16 slot, and I plan to put a Radeon RX 570 on the x4

candy pop slot PCIe cards can always operate in PCIe slots with the same or more lanes than the card For example, an x8 card can operate in a slot with x8, x16, or x32 lanes

candy boom slot Have you ever thought if you can plug PCI Express cards into x16 lane slot? In this video Fortunately, if you have smaller PCIe cards, they can fit into bigger PCIe slots For example, a PCIe x1 WiFi card can fit into PCIe x4 slots