I have this: http://www.amazon.com/gp/product/B006WAGGUK?refRID=DEW7BP85DKGQEBZB56NM&ref_=pd_cart_cp_2_3_p stick of RAM in my system if I buy another stick of the same kind, can I just put the second one in and be fine? Or do I have to take out the current one and put in the 8GBx2 kit?