you may want to get the speccy app and check your tiiming on the 2 sticks you have already working it is available in the download section here.
RAM upgrade would a little less of an expense if you had the four slots, only having the two slots means the old sticks come out for the new. there goes two ram sticks wasted.
also, faster ram is compatible in slower slots. so the 12800 would work in the 10600 mobo slots which makes the slower slots a bit more desirable.
if the mobo slots were 12800, then 10600 wouldn't function.
the crucial site can scan your mobo also for compatible ram. most users like using that functionality.
whether you have 4gb or 8gb or 32gb. if your system is only using 2.5gb, well, it wouldn't make any difference how much you had.. but most users really like having the extra left over.
upgrading RAM is also a very sensitive task, so many things can go wrong. if what you have already is getting it done, i vote to not mess with it unless you start getting in the danger zone of using most of the ram that is already installed and functional. which is why i suggested monitoring the task manager.
if you really want to invest in a future proof hardware upgrade, the 750ti is what will be most satisfying, followed by the ever so popular solid state hard drive. i think the 120gb samsungs are around $80, and that is something that you will be able to transfer to another PC in the future as well. most users deploy those for their operating system (windows) and also their most used applications, while leaving the regular hard drive for storage.
what i do for my system is have one hard drive just for the OS, and keep it defragged and have it used for nothing else, then have other hard drives for everything else. it works for me, my boot time is minimal, but nothing as blazing fast as a solid state drive.
Edited by synergy513, 01 May 2014 - 12:27 PM.