Hi Fabio,
whether 5960X is worth the price depends on your budgetary means and how many other machines you have. Unless you already have formidable render farm, I think of powerful workstation as good investment as well.
I don't think the same of Asus X99-Deluxe board, which unless you know exactly why you would need it ( dual lan NICs, extreme amount of inputs,etc..) you can either go for Asus X99-S which is the same Deluxe board without dual nics and few less contact,
or even "vanilla" Asus XX9-A. They all provide equal overclocking capacity mostly.
Not much to say about Strix 970, it's considered decently silent compared to reference cooling, which is imho important.
2400 vs 2133. It's worth considering also latency timings, i.e CL15 in case of yours. Lesser timing, the better. Sometimes lesser frequency with lesser timings provides same performance as higher frequency but higher timings.
Nonetheless, the actually memory performance matters very little for most tasks today, esp. CGI/Rendering, where it makes about less than <1perc. difference. Rather saver money here and look for good deal.
NH-D15 and Fractal Define is my favourite combination, although lately, Fractal introduced excellent water cooling, called Kelvin S36, which is litterally the best (most powerful while very silent) close-looped system available.
Since it's 360mm (3x120mm fans) big, it fits only Fractal Arc, not Fractal Define and would also add some price, while enable keeping 5960X in 4.5+ GHz territory in better temperate and noise level than NH-D15 would.
Just something to ponder upon.
850 Pro 256GB - Very pricey, but imho worth it. Due to 3DNand, will also last you forever.
1TB HDD - Unless you have NAS storage or file server, 1TB is perhaps far too conservative. Go for at least 2-3.
PSU- What matters is, reputable brand (Seasonic, Corsair (which is also Seasonic mostly), BeQuite!, Goldflower,..) , wattage (overclocked 5960X goes into 300W territory, 970 goes slightly above 200W I think in full performance, STRIX is also clocked higher by factory), you're looking at 650+ W to be on the safe side but not going overkill, efficiency 80+ Gold+ (for a workstation at this price level 2k+ euro, only Gold and Platinum quality makes sense).
If you can't decide, just buy Seasonic.