My CPU, its cooler, RAM and mobo are all 7 years old now, and since they bottleneck some of the newer games, i think an update is due. I want a quiet gaming system, that will serve me for years to come, just like my old has. Budget is around 650€ (comparable to dollars where i live), willing to spend more or less, if anyone has a convincing suggestion to do so. I'm especially curiouus if 4 cores will be enough for future games. New monitor is 1440p @ 60hz, headphones are HD 558 50 Ω. Colour theme is black with possible yellow or dirty colour highlights (think Noctua fans :))

Current specs, red marks parts that i mean to replace.

Case: Define R5
PSU: Corsair RM850
GPU: 7970 3GB Sapphire with 2 140mm Noctua fans (plan to buy the next generation 400€ GeForce when it comes out)
SSD: Intel 250GB
HDD: WD Green 3TB
CPU: Intel Core2 Quad Q9550
Cooler: 90mm Zalman
Mobo: Asus P5Q
RAM: 8GB DDR2 800Mhz

What i would buy:
CPU: Intel i5 6600K
Cooler: NOCTUA NH-D15
Mobo: ASROCK Z170 Extreme4 DDR4
RAM: CORSAIR Vengeance LPX 16GB

Any comments on suggested setup are appreciated.