PSU is a bit overpowered, you can easily get away with the 650W version. If you want to cut the price you could consider the MSI Z270 SLI PLUS or Gaming Pro Carbon.
Parts look really good though, you'll enjoy this rig for sure!
The parts that King Dranzer listed look good but I would definitely go with at least a 500GB SSD, M.2 would be even better but its also more expensive ofc.
And dont forget to include a SLI-bridge.
Right-click on speakers (bottom right corner of the screen) and select Playback Devices.
Here you can enable the speakers you wish to use or disable the ones you dont want to use.
I'm not sure if its possible to output sound over multiple sources but if its possible the option should be there.
Rotary connectors with a seal are leak proof even under high pressure, just like the brake lines on a motorcycle for example. Its a really common thing in machines with hydraulics etc
For gaming the i7-7700K gives the best results so I would go with that if gaming is your main focus.
The 950 Pro is slower and more expensive than the 960 Evo. The 960 Pro is roughly 20% faster than the 960 Evo but also 30% more expensive. I would personally go for the 960 Evo 500GB because the...