King_34 :
12 is an odd number for memory it's usually 2x4 or 2x8.
I think I installed a spare 1x8 on top of the stock 4gb, there shouldnt be a problem right?
Not a problem.
8gb will run in dual channel mode, the odd 4gb will be single channel.
Unless you are heavily multitasking 8 or 12gb is plenty.
Ram speed is not important to real app performance or fps.
Here is a study.
http://www.anandtech.com/show/7364/memory-scaling-on-haswell
If you want, check out your hard fault page rate in windows task manager; it should be near zero.
Your cpu can handle a much stronger graphics card than a GTX1050ti.