Hello i have 2 modules of same model ddr3-1333ghz in dual channel. I have in total 8gb,i want to amply to 12Gb so my question is, i have 4 slots, if i put another 4gb module of the same model in third slots, will it broke the dual channel?? should i put it on 2gb in the another 2 slots to make another dual channel?? how it works?