Is a MacPro3,1 x16 slot PCIe or ?

PCIe cards larger than the PCIe slot may fit in the smaller slot but If your motherboard only supports PCIe , the card will only

Two types of PCIe slot on an Asus H81M-K motherboard Various slots on a computer motherboard, from top to bottom: PCI Express x4; PCI Express x16; PCI Express

slot sisal app Primary riser cage connector, connected to processor 1 or the southbridge PCIe 3-slot riser cage* PCIe 2-slot x16 riser cage 1

super 126 slot Go in to BIOS and Set PCIE to AUTO or Gen 4 it may be getting hung up on the gen 5 PCIE slot So boot to bios from second slot