RickH

I've been using Corsair LPX 3000MHZ on a Ryzen 7 1800X since January 2018. The Ram runs at 3000mhz, no faster. I've never had any issues with the RAM. If I was to get ram over, I'd probably get the 3600mhz corsair ram. 
 
https://www.amazon.com/Corsair-Vengeance-3600MHz-PC4-28800-Black/dp/B01AKWSUOU/ref=sr_1_1?s=electronics&ie=UTF8&qid=1534552367&sr=1-1&keywords=Corsair+Vengeance+LPX+3600

Power supplies are one thing it doesn't pay to go cheap on, in my experience... They have to work ALL the time and never deviate, even when the power is potentially unstable... 

It could be a driver problem. It could be something as trivial as the CPU not totally being seated completely. 
 
Try pulling and reseating the RAM and all the installed cards on the MOBO. 3 years is enough time for dust/corrosion to do their work....
 
And time is ticking.... tick... tock... 

{Citation Necessary}
 
On this topic though, I like the S12A quite a bit. I'm curious as to why it's never talked about.

If you haven't run a computer with SSD as the boot drive, you are surely missing out! Set up your SSD for the OS and core utility apps. Use a regular hard drive for where you install your games and other large software. If you want max performance for gaming, you could even install a separate SSD or better yet a striped SSD RAID array to radically improve your game load times. 
 
You won't believe the performance difference an SSD as your primary boot/OS drive will make! Seriously, it IS that much of a difference!
 
There are some SSD optimization tweaks for various operating systems, things that will make them more stable and more reliable over time. They're worth an evening's research...