PCI Express 2.0 x16: 1 x PCI Express x16 slot, running at x16 (PCIEX16) *For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot. 1 x PCI Express x16 slot, running at x4 (PCIEX4) *When the PCIEX1_2 or PCIEX1_3 slot is populated with an......