Raid to ahci

Hello all i am glad to become a part of this forum and comunity us i am sub to the tek syndicate chanel in YT and i wanted a lot to be in this forum,but lets not waste time of yours my "problem" is this:

I recently bought a sumsung evo 840 120 gb ssd and made a clean install of windows and programs BUT i look in a lot of guides on line and from sumsung it self that my bios should be turnded to ahci mode to take full advantage of the ssd us i readed which i am not expert to know what is the benefit (only trim).So i tried to switch in bios or in the system throw some setings i readed in web and nothing my bios doesnt show up the mode AHCI at all.So i wonder what is the problem ?Does ahci affect the performance of the ssd or the life span is it worth the time? 

Thanks a lot for you time and i hope i didnt bored you also sorry for my bad english

 

My board is this (http://www.findlaptopdriver.com/specs-dell-ot568r/) with i5 cpu and ati Gpu.