2 x PCI Express x16 slots, running at x16 (PCIE_1/PCIE_2)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIE_1 slot; if you are installing two PCI Express graphics cards, it is recommended that you install them in the PCIE_1 and PCIE_2 slots.
2 x PCI Express x16 slots, running at x8 (PCIE_3/PCIE_4)
* The PCIE_4 slot shares bandwidth with the PCIE_1 slot. When the PCIE_4 slot is populated, the PCIE_1 slot will operate at up to x8 mode.
* When an i7-5820K CPU is installed, the PCIE_2 slot operates at up to x8 mode.
(All of the PCI Express x16 slots conform to PCI Express 3.0 standard.)
2 x PCI Express x1 slots
(The PCI Express x1 slots conform to PCI Express 2.0 standard.)