help over clocking ram on alienware 18(2013-2014 model)

guys, I need help

I am on bios A10, currently I have ddr3L rams, 4 of those. They are from Samsung with the current timings

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I am trying to overclock it to 1866MHz or 1867MHz

I see that I cant change the voltage for ram in my bios, is there any other way? And What timings should I set the ram at?

I also have XTU but the voltage reading is wrong for some wicked reason....

help over clocking ram on alienware 18(2013-2014 model)