Gaming PC under 900euro ?

Solution
Decent but you can get a 1070 in a build for that kind of money.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor ($219.99 @ Amazon)
CPU Cooler: CRYORIG H7 49.0 CFM CPU Cooler ($34.89 @ OutletPC)
Motherboard: Gigabyte GA-Z170-HD3 ATX LGA1151 Motherboard ($85.66 @ Newegg)
Memory: Team Elite Plus 8GB (2 x 4GB) DDR4-2400 Memory ($62.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($49.33 @ OutletPC)
Video Card: Zotac GeForce GTX 1070 8GB Mini Video Card ($374.99 @ Amazon)
Case: Zalman R1 (White) ATX Mid Tower Case ($35.98 @ Newegg)
Power Supply: Corsair CXM 550W 80+ Bronze Certified Semi-Modular ATX Power Supply ($43.98 @ Newegg)
Total: $907.81
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-03-23 09:35 EDT-0400
 
Solution
This will get you more for your money and still have high quality parts.
PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor (€336.44 @ Amazon Deutschland)
CPU Cooler: CRYORIG H7 49.0 CFM CPU Cooler (€38.84 @ Amazon Deutschland)
Motherboard: Gigabyte GA-Z170-HD3 ATX LGA1151 Motherboard (€112.40 @ Mindfactory)
Memory: Kingston Savage 8GB (2 x 4GB) DDR4-2400 Memory (€69.77 @ Amazon Deutschland)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (€51.04 @ Amazon Deutschland)
Video Card: Gigabyte Radeon RX 480 8GB G1 Gaming Video Card (€231.67 @ Mindfactory)
Case: Cooler Master MasterBox 5 (White) ATX Mid Tower Case (€67.12 @ Amazon Deutschland)
Power Supply: SeaSonic G 550W 80+ Gold Certified Semi-Modular ATX Power Supply (€89.90 @ Amazon Deutschland)
Total: €997.18
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-03-23 14:55 CET+0100