It's a good build and I highly recommend X79 for higher-end systems but I really do not like the Level 10. 1200W is a bit overkill unless you're running like 4-way 680 SLI. You could get a 1050 and be fine.
I don't care much for the Level 10, but the Level 10 GT is a very nice case, though a bit expensive. A fiend of mine has one and I will be using one on my new build. Lots of room, lots of features and it's a lot more interesting than a typical "box" case.
More on topic, the build looks great but for a build of this caliber, I would seriously consider an SSD for a boot drive.
i hate the level 10 one of the ugliest things around so many better cases for less antec, silverstone, corsair to name a few brands with plenty of models from them, i wasnt aware they were doing 4 gb 680's, but nice build all the same. more money they i am willing to afford