multiple RAM memories are working better than one?

Solution
If it is not a Intel X99 based system then get a 2x8GB kit, otherwise you can consider that 4x4GB kit for extra menory bandwidth (if you need that). Gives you the option expand memory later on without ditching the old kit.


one more question: will i get much bettr preformence by buying 2400 mhz kit instead of 1600 mhz.how it will actually affect the performence?
 


It depends on program/game and what system you are using, AMD systems gain more from faster memory. If the price difference is small get the 2400MHz kit.
 


i got an Intel Core-i5 4590 3.3ghz CPU and Gigabyte Z97MX gaming-5 mobo what you will consider me?

thank.