@ ars.arch01: In order to stay within budget and to sick with Intel the i7 8700K is the only realistic option.
From what I can see of German prices in PcPartpicker dual Xeons ( E5 2630 V3 or V4 )will cost you about 640 Euro each, putting them out of reach and making performance comparisons with the i7 8700/8700K pointless, the same goes for an i9 79XX, even the cheapest 10 core variant is going to cost about 900 Euro, again, putting it out of budget.
In the meantime here's a modified i7 8700K build:
PCPartPicker part list / Price breakdown by merchant
CPU: Intel - Core i7-8700K 3.7GHz 6-Core Processor (€332.94 @ Mindfactory)
CPU Cooler: Noctua - NH-D15S 82.5 CFM CPU Cooler (€75.04 @ Amazon Deutschland)
Motherboard: MSI - Z370 GAMING PRO CARBON ATX LGA1151 Motherboard (€164.59 @ Alza)
Memory: G.Skill - Trident Z 32GB (2 x 16GB) DDR4-3000 Memory (€353.43 @ Mindfactory)
Storage: Samsung - 860 Evo 500GB 2.5" Solid State Drive (€114.51 @ Amazon Deutschland)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive (€57.80 @ Amazon Deutschland)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive (€57.80 @ Amazon Deutschland)
Video Card: Gigabyte - GeForce GTX 1070 Ti 8GB WINDFORCE Video Card (€497.94 @ Mindfactory)
Case: Phanteks - Enthoo Pro M ATX Mid Tower Case (€79.90 @ Caseking)
Power Supply: SeaSonic - FOCUS Plus Gold 750W 80+ Gold Certified Fully-Modular ATX Power Supply (€98.35 @ Amazon Deutschland)
Operating System: Microsoft - Windows 10 Home OEM 64-bit (€96.82 @ Mindfactory)
Case Fan: be quiet! - Pure Wings 2 140 61.2 CFM 140mm Fan (€9.79 @ Aquatuning)
Case Fan: be quiet! - Pure Wings 2 140 61.2 CFM 140mm Fan (€9.79 @ Aquatuning)
Total: €1948.70
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-06-04 20:04 CEST+0200
Kept the 'K CPU, even if you don't overclock it runs a little faster than the non 'K' variant.
Changed to the big Noctua air cooler, it's cheaper than the H100, very, very quiet, the design is offset so it'll clear ALL the memory slots AND the top PCI-E slot and has none of the potential maintenance and reliability issues of a closed loop water cooler.
Better motherboard, IF you decide to overclock this is a top class part for the job, if you don't, the better voltage regulation and cooling will still help with longevity and stability.
Moved to dual 2Tb HDDs from a single 3Tb unit.
Bigger case, better cooling, less noise.
Added a pair of extra fans, the Phanteks case only ships with one, rear mounted fan so you'll need these!
Kept the Win 10 licence.
Feel free to add/remove or specify parts differently, especially the case and storage.