Hey,
first of all there is a critical error in your setup. that Coffe Lake 8700k processor is not DDR3 compatible! This architecture requires you to go DDR4! Which i would also recommend to scale up to 16 gigs if you are streaming, since streaming takes a good amount of RAM space. Combine that with your Game and say Google Chrome running in the background, your 8 gigs will not be enough.
I would also throw in an SSD, like 250-500 gigs.
Apart from that, the CPU is definetly a good choice when it comes to streaming and your 1070 will be able to handle all modern games on 720p. On not hardcore AAA titles you could even think about 1080p streaming if you scale down your graphics by just a bit.
But you definetly need DDR4 RAM, the motherboards no not even have DDR3 Dimms.
And since you went for an OC board and CPU and a strong cooling solution, i hope you will overclock this machine. It WILL benefit from it.
Greets