thx1138v2 :
The way your question is worded kind of implies that you have only one RAM module or you are considering buying only one RAM module. I recommend you get 2 modules. Otherwise, the dual channel motherboard feature will not be enabled. So If you have 4GB or 8 GB RAM, you will be better off with 2 X 2GB or 2 X 4GB respectively.
Also note that the the RAM must be non-ECC and unbuffered or it will not work in your motherboard. Double check the specifications on the RAM you intend to purchase to ensure that it meets those requirements. Sometimes RAM that does not meet those requirements is sold cheaply because there is not as much demand for it.
I'm planning to replace both of my sticks, they're some cheap unbranded RAM that came with my PC and after a year, my computer wouden't turn on if I didn't switch them around, so I was happy when one of them died since I had a reason to get new ones.
I was just concered that if the motherboard specs says it has DDR3 1600mhz, that it wouden't work with the 2400mhz. I have looked at DDR3 1600mhz RAM's and I would only be saving 20% if I would have not bought the HyperX Beast which I'm fine with, may come useful if I ever decide to upgrade my motherboard to something more quality and that have higher specs, aslong the 2400mhz works in that 1600mhz motherboard, I'm completly fine to pay that little more money.