I have ddr3 4gb x2 Cors veng pro 2133mhz, i have 2 slots more free, if i buy 8gb x2 cors veng pro but 1866mhz it won't work? can i do something do disoverlock it ? so it would be 1866mhz all sticks? 1866mhz in my country costs way less, so i dont want to spend +50eur on same +16gb but just cause its 2133mhz as mines 4x2