I was going through the internet in the search for my new motherboard. And every company is advertising that they have x16 SLI support. But when you read on, you see that is not. The only board that I could find so far was the gigabyte g1 sniper 3. Is there any other motherboard whit this capability? Becouse I intend to build a SLI/crossfire sistem, that will probably be OC-ed.
More about :z77 motherboards support full sli crossfire pcie x16
The Intel 1155 chipset (which the z77 motherboards are based on) only provides 16 PCIe lanes. Any decent mid-range motherboard will allow these lanes to be split between two PCIe slots, allowing each card to have x8 lanes.
Some top end motherboards (like the one you quoted) add a PLX chip which basically allows both cards to run at x16, BUT all it does is give the 16 lanes (which it's limited to by the processor) to whichever card needs it at the time. In otherwords, you don't have 32 lanes, you just have the full 16 given where they're needed. NOTE: the PLX chip does introduce a little latency which actually (very slightly) reduces your performance.
The good news is that there are basically no real word situations where even top end cards require the full PCIe 3.0 x16 lanes. PCIe3.0 x8 is more than enough for any video card.
Even if you get 2x GTX Titans and OC em, they'll run just fine on PCIe 3.0 x8 lanes.
Don't worry so much about the x4, x8, x16s. The performance difference will only be like 0.2 to like 2 fps lost. PCIe 3 vs PCIe 2 is pretty much the same in terms of performance, hoeever PCIe 3 is effectively double the bandwidth available on PCIe 2. In conclusion any motherboard with 2 or more PCIe 2.0/3.0 slots will work fine.