The_Vincent

SFPs are the modules you put into the large ports in the switch and firewall you picked. They are kind of like an adapter which allows you to hook fiber into your gear. 
I guess you could ignore them and just go with "it belongs to cabling which already exists", but it is a significant cost. They are also often times vendor specific (officialy at least). 

Just so that I understand you correctly.
This is not a real build, correct? Nobody will buy this, and it doesn't really have to be functional. Or is this a list for an actual build?
 
The most noticeable issue I can see is that you have no SFPs for your firewall or switch. It's generally not best practice to mix vendors like that either (SonicWall and Netgear). You usually try to stick to one vendor.

The 8700/k is choice for gaming if you're going Intel. It's cheaper and there's literally nothing in it when it comes to performance between them. 6 cores 12 threads with great gaming performance is better than 8 cores 8 threads with no hyperthreading and great performance.
 
Low-end intel is something like an 8400, midrange intel is 8700k and high-end intel is 9900k. There is no space for the 9700k. It doesn't do anything that the others don't. It's like the 2070, it's a largely pointless product when you can either get vega 64 for cheaper or a used 1080ti for the same or slightly more.

that won't work well, if it even does. you're wasting 404 dollars here already
 
overpriced for the performance it'll give you (it's not enough anyways), i know 25 dollar coolers that do better.
 
boom?
 
name your budget, preferences and country, i'll make something better up for you

The Ryzen APUs would still count as iGPU, and they could offer some basic performance that wont totally suck. Look up some reviews of 2400G for example. https://www.anandtech.com/show/12425/marrying-vega-and-zen-the-amd-ryzen-5-2400g-review
 
As for the question if quad channel ram would help, then yes to an extent. It's always a balance of both bandwidth and also the cores in the GPU. If you swing much one way, the other side becomes the bigger limit. This is in part why even if they wanted to, they can't put too much GPU in a CPU socket as they'll both fight for limited ram bandwidth. Also quad channel doesn't make sense in lower cost builds even if it were to be supported.

There is no APU/iGPU on the market that supports quad channel memory. Additionally, graphical performance is primarily determined by the number and speed of stream processors, rather than the speed of memory.