Go over to andandtech forum and check out the article about your Question. I just got done reading it. Not the most sexiest read. Not that you need too. It might just need to be TOLD to work at the stated speed on the box. Sorry I do not have the link I cleared my browser on close before hopping over here.
But to answer your question from what I read over there is YES. And most if not ALL users, do need to SET their Ram according to the article.
Just because it says 2400 mhz on the box does not necessarily mean that when you stab it into your MOBO you are good to go. It needs to be done in the BIOS. How to do it ? I do not know Yet.
IE: I am looking at Kingston VS Gskill... reading about Latency and Clock timing. The timing that one could pay upwards of 200 bucks may never even be noticed. (pends on applications) Check out the article it was informative.
The bottom line I found when selecting Ram is warranty, price, quality. The Latency one might pay an extra 100 for, we are talking about Nano Seconds. So the time it took me to reply to you, I could have NOT spent the extra hundred and waited five seconds longer for the "word" =64bits of info to be written. While rendering 20 minutes of video. However if playing video games, you might become 1 second quicker then "King Cheese" on the Battlefield. I know cool gamer tag...However you are delving into splitting hairs from what I read. FWIW...
^ What?? Seriously that's the second post I have read by you referencing a weeks old Anandtech article that does not even apply in this case. Read more before trying to "help".
You have an H61 motherboard. The max RAM speed it will support is DDR3 1333. You can not overclock it with that board. You also can't overclock your CPU both because of the board and the fact that it's an i3.
Look, your CPU has an integrated memory controller ( IMC ) and it can not use RAM faster than DDR3 1333. With an i5 or i7 and a P67, Z68, Z75 or Z77 motherboard you have more freedom when it comes to memory. BUT, these chips still have an IMC that just does not need RAM faster than DDR3 1600. Faster RAM yields very little gains and is just a waste of money. You will never see a difference anywhere but benchmarkng programs unless you process video professionally. Then a case can be made for faster RAM. In gaming there will be 0 differece between DDR3 1333 and DDR3 2133. Don't worry about it. Your motherboard an CPU are just fine as is. As I said above you can't run anything faster anyway.