[SOLVED] Asrock z77 extreme 4 for two way SLI

Official Asrock z77 extreme 4 spec page says:

- 2 x PCI Express 3.0 x16 slots (PCIE2/PCIE3: single at x16 (PCIE2) / x8 (PCIE3) or dual at x8/x8 mode)

What bothers me is that it says "single at x16" and "dual at x8/x8".
Is this how its supposed to be or are there motherboards that have better support for two way SLI?
Thanks beforehand!

P.S. My desired cards are two 980 Tis.


Edited by GameBurger - 24 Aug 2015 at 2:07am

Yes that is how it is supposed to be, and is all it can be, without additional help.

All the Ivy Bridge processors you can use in a socket 1155 board like the Z77 Extreme4, supply 16 PCIe 3.0 lanes. The Z77 chipset provides PCIe 2.0 lanes, which are not used for video card slots.

So use two video cards in SLI, sharing the PCIe 3.0 lanes, and you get x8 in each slot.

If you are using a Sandy Bridge processor, you will only have PCIe 2.0 lanes from the CPU.

With a CPU providing PCIe 3.0 lanes, no video card can use all the bandwidth of an x8 lane.

A few high end boards have PLX PEX chips, that multiplex the PCIe 3.0 lanes between three x16 slots, but that is for triple SLI at x8.

If you really want two x16 capable slots for dual SLI, you'll need to get an X99 or X79 board, and a HEDT processor.