16GB ram is overkill, I like it.
I could have fun with a rig like that!
I would personally drop the HD 7970 and get an NVidia 670 or 680 (if either can be found there). To quote PCMag.com regarding 7970 vs 680 "...the Nvidia card delivers more satisfying performance in most games, costs $50 less up front, and because it uses significantly less power than the AMD card it will also save you money in the long run."
The rest looks good.