8GB is the optimum amount of memory for gaming and will give overall better system performance. As apps and games get even more resource-hungry in the future, having more memory will become even more important.
I recommend 8GB for any new system. The extra money spent now will reap benefits every day, until you need to upgrade to a totally new system.
The speed of the RAM is actually less important than the amount. If the choice were 4GB of 1600 versus 8GB of 1333, I would choose the 1333 RAM.
And what is the guy above me talking about? Why is a moderator posting nonsense?
So many times we get questions like we're mind readers or something, only partial information is supplied and we have to either cover every possibility or wait for the OP to post the operating system he's planning on playing his games on.
So much missing information, what games are we talking?
Crysis 2 or Pac Man etc., etc., etc.
Is it a 32bit OP/SYS or 64bit OP/SYS?
And I posted nonsense, because that's just me, and I'm in a good mood!