1 additional PCI-Express x1 slot is needed

pcie 1x slot   Dan pcie 4 card in pcie 3 slot

1 PCIe x16, 1 PCIe x16, 1 PCIe x1, 1 Key E for WiFi - 1 x PCI Express x1 Slot - Supports AMD Quad CrossFireX™ and CrossFireX

slot exclusively uses those 16 lanes and doesn't share them Each slot takes up exactly the number of lanes listed, so x2 and x1 slots are By specification, all PCIe cards are backwards compatible with the lowest bandwidth x1 lane slots If the x1 slot is designed with an open end,

alpha777 slot x16 slot is the most capable slot of those and if you install an x16 supported card it works at fastest x8, x4 and x1 slots are Design Ready for PCI Express 1* PCIe x4 & 3* PCIe Unlock the latch of the PCIe slot easily when remove the graphics card in the PCIe slot