Give Zak (my son) a break.. He's just giving his slice..
Anyway, I think if your rendering the Firepro's or Quadro's have to take priority especially with the high budget. They are designed for rendering and CAD use, Yes they have a hefty price tag but they will be a lot faster at rendering these big complex models than most consumer gaming GPU's.
If i was to spend 2k+ on a PC i'd feel cheated if i was still on 1155.. Though im not sure the 3930k is the right way to go either, the 3820, while being simular to the 3700k just makes more sense to me, for this build.
Wrong, oh so wrong. The vast majority of rendering is done on the CPU.
A 3939K is a far more suitable CPU than a 3820, and it's a waste to go X79 and then just get a quad core.
FireGLs and Quadros (no apostrophes!) don't take priority here. They will not be a lot faster at rendering these big complex models, because, well there won't really be any if it's interior scenes and furniture renders, and secondly, the GPU won't be used for final production renders, they are used primarily for the view port render.
Since they aren't working on complex models, a pro card is an utter waste of money.
Depending on what they're using for rendering, the card won't make any difference again, they could be using VRayRT but that's accelerated by OpenCL, so can be used on any GPU and would excel on a recent AMD GPU more so.
But, if they're not using anything CUDA related (which they're probably not) then the CPU and the CPU alone will be doing ALL of the rendering, not the GPU.
Maybe you should think I should give him a break, but he's trying to give advice about a subject he doesn't understand, just like you are now (again, no offense intended), and when it's such a subject you have to be sure you know what you're talking about if you want to give advice as some one could buy based on your incorrect/poor advice.
So a 3930 with a gaming GPU is far more appropriate than a 3820 with a Quadro or FireGL, any else is just plain bad advice.