I haven't heard of the G.Skill neo series, I chose the flare X for the same reason made for Ryzen compatibility. If it is indeed made for Ryzen compatibility it might be a good idea.
Of note it's not that G.Skill has some special sauce for Ryzen it's just what I used and I know works well. Corsair makes great RAM but the LPX series seems to have Ryzen issues.
So one the first question, that is a difficult to narrow down because there are so many things it could be. Component wear, higher room temperatures than before, software updates / patches, driver updates, application updates, data corruption, so many things...
If you didn't know what XMP is then you probably didn't enable it... That means if your RAM is having issues it might be at JEDEC defaults which is really bad if it is rated for 3200.
I'm leaning towards power issue now since the RAM is running at default speeds no XMP, that RAM should be fine at default speeds even with the Corsair LPX XMP issues. The thing is your system's weak point is that power supply. 600 Watts is fine but maybe in a better brand. Rosewill is basically a generic brand and with power supplies that matters in my personal experience.
Get a Seasonic or one of the better quality Corsair or EVGA units.
