The Gigabyte Z68X-UD3H-B3 comes with two PCI Express x16 slots, three PCI Express x1 slots, and two standard PCI slots.
The two PCI Express x16 slots are connected directly to the CPU integrated PCI Express controller. When only one video card is installed, the slot works at x16, but when you install two video cards, each slot works at x8 speed. These slots support both SLI and CrossFireX technologies.
If you install a dual-slot video card in the first PCI Express x16 slot, you will “kill” one of the PCI Express x1 slots. If you install a dual-slot video card in the second PCI Express x16 slot, you will “kill” one of the standard PCI slots.
It is important to understand that Intel chipsets no longer support standard PCI slots, and the PCI slots are provided by an ITE8892 bridge chip.