Your CPU only supports ram up to 1333.http://ark.intel.com/products/52213
I don't know if that is the primary cause though, and I doubt it, since it sounds like you werent having problems before.
What GPU do you have?
Might want to try updating the bios: http://www.gigabyte.us/products/product-page.aspx?pid=4338#bios
And checking to see if your ram is on the memory support list: http://download.gigabyte.us/FileList/Memory/mb_memory_ga-h77n-wifi.pdf