4 x 4 slot ✓ x4 slot

4 x 4 slot PCIe UD Slot X： PCIe x16 slot with 10X strength for graphics card Compare Ultimate Scalibility: 4*PCIe x16 slots for Multi-GPU and 4*PCIe x44 x 4 slot This slot can be used as x16, x8x8, x4x4x4x4 using Bifurcation In Case of my Truenas install a 4 x NVME Board was used with the x4x4x4x4

4 x 4 slotThe following image shows the PCI connections of the motherboard used in DuroPC's IMB540-4 Notice 'SLOT 13' are PCIe x16 slots but only Slot 3 has an x8

4 x 4 slot Sonnet 4x4 and McFiver PCIe Cards