In my defense, your GPU of choice is suffice if you're doing moderate gaming, even at 2k resolution you should expect at least 60 fps which is standard, but the more frames the merrier. 8GB for your GPU is plenty, I plan on upgrading to an 8th gen i7, and figured even a 1070ti is more than good enough for most triple A titles. I'd rather have a bottlenecked GPU than CPU, only other thing you may want is some more SSD storage with all that memory! Other than that, nice build, enjoy.
Obviously the AMD chips are way less expensive than Intel. I am sure if he wanted to construct a Ryzen build he would have. Not everyone focusing on under $600 builds are gonna go with Ryzen. As you can read from his build description if you even read it.
It would rely on the fan splitter so I would check the specs for that, your motherboard will only use the connection really for monitoring fan speed.
If you mean daisy chain them by connecting all of them to the same power cable while having multiple splitters, then yeah that should work, and your PSU should definitely be able to power three different splitters. Hope this helps.
Nice build, I really like that you embedded fans into the computer cabinet for your desk. The only thing I can comment on is the fan splitter.
I would check how many amps your mb fan headers support and check your fans power requirements (since the power requirements vary with different fans). If you plug in too many fans to one header, you can bottleneck the power requirements.
Keep on Building!