Riser Cards and PCIe Slots

Can someone explain me the PCI-E slot variations & sizes pcie slot length Two single-wide full-length x8 gen4 slots One single-wide half-length x4 gen3 slot preconfigured with the Apple IO card The Apple Thunderbolt pcie slot meaning Also, PCI slots are the same sizes for all devices PCIe slots differ depending on which form factor it accepts The longest would be the 16-lane slot and, the

pcie slot cover With our Max series, which already provides you with 8 tuners per card, you can expand a single PCIe slot for up to 48 tuners The backplane is designed for