GB Z77X support 1866mhz ram?

any one know?

Your MOBO says DDR3 2400 OC that mean it might be supported. But i suggest you to check your MEMORY support list cause those are compatible with your MOBO.

I had the same question. I was thinking of buying some 2 4GB sticks of Crucial memory for this exact motherboard so I emailed Gigabyte and they said, "If the memory isn't listed on the memory support list, then we can't guarantee you, please check memory finder for the "GA-Z77X-D3H" at Crucial website for validated memory."

So I checked Crucial's website and 1866 memory is listed as supported for this motherboard http://www.crucial.com/store/listparts.aspx?model=GA-Z7...

I don't know if it'll show up in the BIOS as 1866MHz stock or OC from 1600MHz but it seems to be supported so at the very least it should work.