Vapor3oN

Make sure the motherboard comes with a BIOS version that supports the 2600 or that you can somehow update it. :)

It's a nice build. What are you planning on playing? I have a i5 8400 and a 1070 so we're kinda similar in gaming performance and honestly, for very demanding games like PUBG you can get 90-100 in 1080p ith a mix of high-medium settings so i dont really see a point in 1440p unless you want to decrease settings to improve the framerate enough to make it worth it. On the other hand, if you play stuff like Overwatch, Rocket League or CSGO a 1070 can easily run those at 140 fps so I would see more sense in getting a 1440p monitor. Is there any reason you're going for the 1600 instead of the 2600? The 2600 has a bit better gaming performance. I would go for it and skip the RBP mat to keep it at the same prize but that's just my 2 cents.

With that you're gold to play the games you mentioned at 144hz. The only thing I would try to get is a 8GB RX 50 and not the 4gb one. The ASRock one is pretty cheap and not that much more expensive on : https://www.newegg.com/Product/Product.aspx?Item=N82E16814930002&cm_re=RX_580-_-14-930-002-_-Product it's not that much more expensive that the one you selected. Also, if it were for me, I'd try to go m-ITX for a smaller build but m-itx mobos have a little bit of a price difference and you'd really have to pick your case + gpu together so you get a card that fits on the m-itx case you selected. I would suggest getting the HDD over the SSD for now , you can buy the SSD later. It's better to have a slightly longer windows load time than to run out of space and see what game you have to delete before you can download a new one. That sucks