I NEED TO KNOW THAT WATS A DIFFERENCE BETWEEN 1333 VS 1600 MHZ I NEED RAM FOR GAMING LIKE BF3,CRYSIS2,3 etc SO WHICH WOULD BE BETTER.
More about1333 1600
There is not much difference. 2x2GB 1333 will game fine. If you can afford it, you go 2x4GB 1600, but you will only notice like 5% performance increase at most, even if you may be spending like way way more than 5%.
There is no appreciable difference, but its only a matter of a few dollars between 1333 and 1600Mhz, get the faster RAM.