Question about AOC Agon Ag352ucg6

Did you use the display port connection on the mainboard or on the graphics card if it is true that you used the connection on the mainboard, try it directly on the graphics card.
And I have from time to time such a problem that my Ram complains with some monitors, if the Ram was labeled with e.g. 3200hz I would recommend to underclock the Ram and only afterwards go back up to 3200hz.