See first gen cpu are 3digit model no like i3 530,i3 540 etc while 2nd gen have 4digit and it will start from '2' like i3 2100,i3 2120 and 3rd gen will start from '3' like i3 3220,i3 3225.remember 1st gen cpu uses socket lga 1156 whereas 2nd and 3rd uses lga 1155.3rd gen i3 is best among all.