(1) Strange you used corsair RAM at all. Ryzen & corsair memory issues have been around since day1 gen1 was un-bootable at all for months. More specifically the problems have been with LPX but not limited to just it with corsair RAM. The problem is lootbox way they do IC and RAM with same timings but change version number. This allows for some users to have no problem and others like yourself to have every problem under the sun with identical specifications. If the version number and specification is not specifically on the QVL you can be in trouble. Not to mention that most sellers don't even display the version number online. Sandbagging any active o/c forum would show there are issues with corsair ram particularly LPX and ryzen.
Was the RAM on QVL for specification & version - no well you should know better (Intel or AMD both have fair share of this crap).
The recommended RAM is g.skill & Crucial Ballistix (if your brand man) or (more technical) get Samsung b-die if you want the best and that coming from someone that has built computers for 38 years and owns 1800x, 2700x, 3900x & 4800h and would not recommend corsair RAM for Ryzen ever.
(2) - Don't use your board. No comment.
(3) lol Intel, CPU & gpu ???? - Honestly if your that rusted on Intel than stay there and be happy. You don't mention cooling solution on the CPU, did you use stock heatsink, how much burn in time have you completed for the CPU, did you use the stock heatsink material or replace it and if you replace it how did you do this.
So lets look at that gpu choice
https://www.tektick.com/reviews/xfx-rx-5700-xt-raw-ii-review/ https://www.youtube.com/watch?v=QvAO_6UdF44 https://youtu.be/SF1Zs3unEto they appear to run hot in reviews, did you do your homework on your gpu pick or jump on it by price ?
That thing is heating your whole case up. How are you dealing with this issue, what case are you even using ?
Most experienced builders include everything to give people a real example of what they have by providing the whole specifications and leave nothing out. I feel like your 40 years of geek but maybe not as experienced in building. Playing an Intel is better card in your first post proves you don't really understand technology and possibily leading to being argumentative or combative in future posts. Then there is that appeared failure to research, not sure why you didn't do that.
I don't make any purchase blind or on price (price as any metric is **** although it stops me getting a threadripper !)