I right now have 6GB of Corsiar XMS3 DDR31600 CL9 RAM that I bought almost 2 years ago. It's version 3.1. I want to upgrade to 12GB and an online store has this memory but I don't know if it's version 3.1. I want to avoid buying a 12GB kit because it would be cheaper just adding 6GB to my 6GB I already have. Should I just buy a 12GB kit and sell my 6GB or should I just buy the 6GB kit and add it to my 6GB?