You could try to use 2x4gb sticks and see if you can get a higher overclock, I've heard using more than 2 sticks leads to issues and is complicated/interferes while testing, but this is from what I've researched so far, of course i'd want the full 16gb since I paid for it lol.
Also I found the higher overclock the lower the ram is always better, for me my ram is 1600mhz at 1:4 ratio, i went to 1:3.33(<-- something like that) which is a step below 1600 which is 1333 but since i overclock with the FSB i get 1466mhz which is not much behind the original.
I also tried lowering it down a step further while rasing my overclock it 3.75GHz and it helped alot but I still failed Prime95 after a couple hours.
If i were you i'd return to stock, then take it step by step and everytime you raise the FSB by 5-10 run prime for 10-15min and if you pass keep raising it till you start to fail almost immediately, then I would start bumping the voltage a little by .010 till it starts passing longer and longer, also write down everything you do on paper so you can return to a certain setting and you dont get lost at what you did.
Im still new at overclocking but this is what i've been doing and its working so far