Hi finite.....Welcome to the forums.
That is a good build but I would make suggestions.
The Enix case I'm sure is popular and you do seem to be locked onto it, which is fine, but it is cramped, the airflow isn't as good as other cases and it can be very noisy even without the performance fan package you picked. On the plus side, the newer cards like the gtx680 exhaust most of their heat out the back of the card and out of the case which helps alot in case cooling.
Here's a link to a very well done review of the Enix, just to give you the most info.
The ram speed I would drop to 1600Mhz. The faster 2133Mhz speed you'll never see any gains in gaming and the higher speed is more unstable with overclocking.
Not sure if the Enix case can fit a 240mm rad, but if it can, the stage 3 , 120mm rad cooler I would upgrade to stage 4 for its better parts and larger 240mm rad. Or , drop to the stage 2, 240mm unit for the larger radiator, no maintenance and cheaper. If you go to stage 2 then the H2O tubing and UV lighting wouldn't apply.
The gtx 680 is a great card. Without knowing the monitor size or resolution it's impossible to say if it will meet your needs for high frames at high settings. For a 23/24" monitor at 1920x1080, the single 680 will play most games on high. Ultra settings would be a problem with games like Crysis warhead and Metro2033 for example and stay above 60fps.
If you have no need for sli in the future then the 750HX psu would do it and save you $100.
Hope this helps and good luck.


Edited by bprat22 - 16 Jun 2012 at 11:39am