I only play Counter Strike GO. My kids play Paladins, Overwatch, Minecraft, Roblox. So no need for high end specs. The purpose of the build, above 200 FPS low details in CS GO. I got 250 on SteamOS, 1920x1080 low details. SteamOS was my first OS choice. It took me a day to install and get it started (figure out AMD driver issues). I will get an extra SSD and buy Windows 10.
Thermaltake Core V1 - I always wanted a cube pc. So I started the build by getting this case. Front 200mm fan is impressive. The layout and quality are amazing.
MSI Z270I - mini-itx motherboard to fit the Thermaltake case. From specs, powerful and good for OC.
I5 7400 3.00GHz Kaby Lake - decent price and performance for a mid range gaming pc. Would not spend more than 200 Euros on a CPU.
MSI RX 480 Gaming - one of the best performance price ratio. RX 580 was just released, but not too much different. It was on sale so I got it for my build. It seems huge for the case, but fits perfectly. I had to remove the case front to install it, but it was very easy. In idle the temperature is 33 ° C, on load 73 ° C. Added a magnetic filter in front of the two large fans.
Corsair Vengeance RGB 16GB DDR4 3000MHz CL15 Dual Channel Kit - they look very nice.
Noctua NH-U12S - too tall for this case, but I got it anyway. I drilled holes in the case plastic top panel. See pictures. It keeps the CPU at 36 ° C in idle and 53 ° C in load.