PCIe kaart in PCIe slot?

In this video, I tested the PCIe gen 3 slots to see if there is any performance difference when

3 x Audio Jacks Expansion slots ・1 x PCIe x16 SafeSlot core+ ・2 x PCIe x16 1 x LPT header 2 x AURA Addressable Gen 2 headers 4 x DIMM ・DDR4 5333

pcie 4 gpu in pcie 3 slot PCIe x16 Slots 1 2 3 4 7 5 AMD B550 Ryzen AM4 Gaming ATX motherboard with PCIe® , teamed power stages, Intel®

pcie 20 x16 slot PCIe is backward compatible with the PCIe and older versions, so devices designed for PCIe can still be used with PCIe motherboards, although at