not sure if 1300€ is enough for a gaming rig that can take advantage of the 1080, and also include monitor.
PCPartPicker part list:
https://de.pcpartpicker.com/list/gbJv6s
Price breakdown by merchant: https://de.pcpartpicker.com/list/gbJv6s/by_merchant/
CPU: Intel - Core i5-8400 2.8GHz 6-Core Processor (€187.59 @ Amazon Deutschland)
Motherboard: ASRock - Z370 Pro4 ATX LGA1151 Motherboard (€106.99 @ Amazon Deutschland)
Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3000 Memory (€180.58 @ Amazon Deutschland)
Storage: Samsung - 850 EVO-Series 250GB 2.5" Solid State Drive (€89.89 @ Amazon Deutschland)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (€43.73 @ Amazon Deutschland)
Video Card: Gigabyte - GeForce GTX 1080 8GB G1 Gaming Video Card (€530.00)
Case: BitFenix - Comrade ATX Mid Tower Case (€34.90 @ Caseking)
Power Supply: SeaSonic - S12II 620W 80+ Bronze Certified ATX Power Supply (€62.46 @ Amazon Deutschland)
Monitor: Asus - VG248QE 24.0" 1920x1080 144Hz Monitor (€251.00 @ Amazon Deutschland)
Total: €1487.14
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-02-20 10:27 CET+0100
If the 1080 is already bought and the 1300€ is what you have left for the rest of the components, sounds better.