The ASRock FM2A85X Extreme6 comes with three PCI Express 2.0 x16 slots, two PCI Express 2.0 x1 slots, and two standard PCI slots.
The first two PCI Express 2.0 x16 slots are controlled by the CPU, with the first slot working at x16 when only one video card is installed, and with both working at x8 when two video cards are installed. The third PCI Express 2.0 x16 slot (PCIE5) is controlled by the chipset and always works at x4 speed. You will need a computer case with at least eight expansion slots if you want to install a dual-slot video card in this slot. (Computer cases usually have seven expansion slots.)
The PCI Express x16 slots support CrossFireX technology.