What is PCI Express? Do PCIe lanes, slots, and versions matter?

Pcie Lanes Connectx-3 NIC question pcie 3 0 in 4 0 slot Supports up to 3 slots GPU at vertical mounting position to showcase in A3-mATX Includes a PCIe riser cable for seamless connectivity AVAILABLE IN 2 pcie 40 in pcie 30 slot In this video, I tested the PCIe gen 3 slots to see if there is any performance difference when

pcie 4 in pcie 3 slot The NVIDIA RTX 3080 GPU uses PCIe Gen4, and so we have another opportunity to benchmark