PCI Express Gen4 - 3 slot passive backplane

Why PCI Express backplanes are so expensiveunpopular? pci 4 in pci 3 slot Slot 2, PCI Express x16 ; Slot 3, Slot not available on this board ; Slot 4, Slot not available on this board ; Slot 5, PCI Express x8 in a pcie 40 gpu in 30 slot Important: You'll also have to be sure the motherboard actually has a PCI Express slot implemented The chipset is not a guarantee of that, just an

pcie 20 x16 slot PCIe Gen 3 x 1 PCI Slot x 3 30423052 B-Key x 1 (PCIe