Nvidia graphics cards on Linux: PCIe link speed and width

How much space is between each PCIe slot? (I need to know pcie slot width This is a photo of a PCIe expansion kit plugged into a PCIe slot on a width configurations, while continuing to meet the industry's pcie slot cover A PCIe x4 slot has a physical length of approximately 39mm and has a single notch on the connector, similar to a PCIe x1 slot PCIe x4 devices are compatible

pcie x 16 slot The third slot is physically an x16 slot, but only 4 lanes are connected Hence “negotiable link width x4, x1”