Wow this is almost my exact same build. And I had a lot of instability. I was at the point of going to install 8.1. I did buy a key for 8.1 I already had a disk from my previous build. So I don't know if the key, which I got off ebay for three bucks, actually works. But it is a security blanket.
- Make sure your RAM is in A2 B2. If you put it in A1 B1 all kinds of strange stuff will happen. I guarantee it.
- There have been a lot of reports of multiple AV systems having stability problems with Win 10 update 1903. So if you have other AVs working try uninstalling the anti-virus and just using Windows Defender. Google your AV and "windows update" and see what you come up with.
- I think it's reasonable to say that there are a fair number of buggy GPUs out there. My computer was crashing when I ran 3dmark benchmark tests (with brand new RX580) but with the old graphics card (R9-380) everything works great. So you certainly might want to try a different gpu if you have or can borrow one.
- My problems didn't begin to go away till I got as far away from MS on line as possible. I did a fresh OS install LOCAL ONLY. To do that when you get to the installation point, disconnect from the internet and decline every option to join any of the kuhrap MS tries to throw at you to make the experience "better." You'll know you've done it right when it asks for a password and then has you give three authentication choices (your dog, etc.) which have NOTHING to do with authentication via your phone on the internet. Once you do that, make a SECOND administrator account with full administrator powers in case you stumble, as I did, into some odd Microsoft/Onedrive situation where they're asking you to make a new account. Stay away from that. In some conditions it will rename your account (on your desktop) and your computer and you'll lose administrative powers. (it will say you have them, but you won't). Anyhow the instant your system is up and running use Edge to go get your drivers. Do that before installing Chrome or other preferred browser.
- Once you have your drivers do a benchmark (like Userbenchmark) just to make sure everything's working.
- If you have purchased a NEW psu and it has modular cables and you are using the modular cables from a previous build that is an extreme no-no.
Since I paid attention to these various things my build has been stable. It is a chore to get Cortana off the internet, where it is constantly trying to send you, and also get it out of your searches but it can be done. There are instructions on the net. The routine that seemed to work best was the one that required me to tinker with the registry.
My seasonic is 850W so I dooubt the gpu issue was insufficient power in my case, can't say about yours.
You will likely fare better with Win 10 Pro or Win Enterprise if you don't have them. Win Enterprise has a different billing system so make sure you know what you're getting into.
This is the procedure that I successfully used to keep the search bar from doing a full internet search (ghacks)
Greg N