Question MSI Z97 Gaming 3 + cpu 4690K - which RAM to choose?

[variasm]

Hello,
I would like to buy a new DDR3 RAM (have one piece 8GB Goodram 1600 Mhz on MSI Z97 Gaming 3 + cpu 4690K) and would like to get you recommendation on which RAM should I choose for my hardware: I'm interested in 2x 8GB but not sure to choose 2133 or 2400 Mhz (if it makes sense to take 2400 at all)?
Thanks in advance for advices!

 

[sizzling]

On DDR3 the benchmarks I saw showed RAM speed made minimal difference. What’s the price of each?

 

[variasm]

As I see price of 2133 and 2400 is similar eg price of 2x set of the RAM from G.Skill is about 100 EUR:
G.SKILL RipjawsX 16GB 2x8 DDR3 2400MHz CL11 1.65V
I I'm not sure if my CPU will work with 2400 Mhz RAM (but for motherboard 2400 is according specification).
So I would like to get any advices.