Socket LGA2011 processors have a total of 40 PCI Express 3.0 lanes for video cards. This allows a very high-end configuration for the PCI Express x16 slots, but the exact configuration used will depend on the motherboard model.
The ASRock X79 Extreme11 comes with seven PCI Express 3.0 x16 slots, allowing a very high-end configuration, thanks to the presence of two PLX PEX8747 switch chips. Slots PCIE1, PCIE3, PCIE5, and PCIE7 always work at x16 speed, so you can install up to four high-end, dual-slot video cards that will achieve their maximum performance. The other slots work at x8. If more than four expansion cards are installed, only the first slot will work at x16; the other slots will work at x8.
When installing dual-slot video cards, you “kill” the slot immediately to the left (looking at the motherboard with its rear connectors facing up) of the slot being used. If you install a dual-slot video card in the seventh PCI Express x16 slot, you will need a computer case with at least eight expansion slots.
All PCI Express x16 slots support both SLI and CrossFireX technologies.
The absence of PCI Express x1 slots is not an issue, since you can use PCI Express x16 slots to install “smaller” cards (i.e., PCI Express x8, x4 or x1).
When installing more than one video card, it is recommended that you install the two available peripheral power connectors. One is located near the first PCI Express x16 slot, and the other is located near the seventh slot. See Figure 2.
In order to accommodate the additional features available on this motherboard, such as the LSI SAS2308 chip that controls eight additional SAS/SATA-600 ports and requires eight PCI Express 2.0 lanes, the ASRock X79 Extreme11 has a PLX PEX8605 switch chip to expand the number of PCI Express lanes controlled by the chipset.