The ASUS P8Z77-V DELUXE comes with two PCI Express 3.0/2.0 x16 slots, one PCI Express 2.0 x16 slot, and four PCI Express 2.0 x1 slots.
The two PCI Express 3.0/2.0 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. Since these slots are controlled by the CPU, they will offer PCI Express 2.0 bandwidth (8 GB/s at x16) when a “Sandy Bridge” CPU is installed, but PCI Express 3.0 bandwidth (16 GB/s at x16) when an “Ivy Bridge” CPU is used.
The third PCI Express x16 slot is 2.0 and always works at x4 speed. If you want to install a dual-slot video card in this slot, you will need a computer case with at least eight expansion slots. (Computer cases usually have seven.)
ASUS did a great job by using different colors at each PCI Express slot, so you can easily identify their speeds: Blue for x16/x8, gray for x8, and black for x4.
The PCI Express x16 slots support both SLI and CrossFireX technologies.
In order to properly accommodate the additional PCI Express devices that are on this motherboard (third PCI Express x16 slot, additional Gigabit Ethernet port, Wi-Fi/Bluetooth card, two extra SATA-600 ports, and four extra USB 3.0 ports), the board makes use of a PLX PEX8608 switch chip. This chip automatically switches the available PCI Express lanes to the devices that need them. On motherboards with too many PCI Express devices, without a switch chip you need to manually disable devices on the motherboard setup in order to achieve full performance on devices connected to the USB 3.0, SATA-600, and Gigabit Ethernet ports when transferring files at the same time.