best gaming computer for 800€ ?

[Fluzzyy]

so im about to buy a new computer and im wondering what would be the best components for 800€ build? I dont necessarily need a whole new computer because i can just upgrade the most important components, like GPU,CPU,RAM,MOBO,CPU cooler, and maybe PSU. So leave me suggestions for the best components for 800 I could save the HDD's,Optical Drive,Case, and maybe the PSU from my old computer if it's powerful enough for the new components. The PSU is: chieftec gps 550ab-a. Ask if you need more information

 

[Specops125]

This assumes you want to overclock and go SLI in the future. If you did go SLI you would need a better PSU at that time, but wouldn't just for overclocking.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-4670K 3.4GHz Quad-Core Processor (€206.85 @ Amazon Deutschland)
CPU Cooler: Noctua NH-D14 65.0 CFM CPU Cooler (€74.90 @ Amazon Deutschland)
Motherboard: Asus Z87-A ATX LGA1150 Motherboard (€128.38 @ Amazon Deutschland)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1866 Memory (€86.00 @ Amazon Deutschland)
Video Card: Asus GeForce GTX 770 2GB Video Card (€313.90 @ Amazon Deutschland)
Total: €810.03
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-01-25 13:15 CET+0100)