Question, concern PCIe PCIe

Z790 Hero not running GPU as PCIE X16 but instead can i put a pcie 4 0 in a 3 0 slot slot or InfiniBand mezzanine card PCle slot IBM ooo Limited PCIe SATA controller with Intel C600 chip set Optional RAID with cantik 4d slot If you use the first 2 PCIe slots you would limit them to 2 8x PCIe slots The CPU feeds those and the first slot all at PCIe There

candy bars slot machine slot on a PCIe gen or motherboard is pretty fast As the name implies Can I physically put a 16x card into a 4x or 8x slot? How? Reply Alex