Help With My Gaming System Build

[badpotato]

Hello, I am planning on building a new pc this holiday season. This is my first time building a PC, so I wanted some advice on my build. Here is what I have so far
http://pcpartpicker.com/p/2cooK
I will be playing fps games like bf4 and Crysis 3 at ultra settings on either a 1080p 120hz or 1440p monitor. I am willing to spend up to $2000 but I would rather keep the budget at the price it is. As far as monitors go, should I wait for g-sync ready monitors to come out? Also, should I go with an r9 290x, rather than a gtx 780? I was wondering whether nvidia's shadowplay and g-syncing would offer a large advantage as opposed to amd's mantle.Thanks for you help.

 

[iceclock]

Gsync or mantle isn't out yet so cannot comment on possible performance.

Your current system looks good but if u plan on getting 2x780s maybe get 850watt ps instead if not the 750watt will do. Looks good buddy

 

[badpotato]

Would I benefit from ram with a lower cas latency/ higher frequency?