Hard to say what the issue is.
One thing, don't bother running your 850 Evo drives in Raid 0. There is little performance difference, and the risk of losing data is exponentially higher if one drive fails. If it was Raid 1, then you'd have your redundancy....but even then, not worth it for our day to day life.
If you think it's the PSU, the only easy way to check that is buying a new one.
Personally, I don't think I've ever purchased a PSU that was less than $180. I typically do a bit of research and look for PSU's that are made of top quality parts. The only PSU's I would NOT trust are the dirt cheap ones.....there are reasons why they are that cheap.
Your issue does make me think it's something software though, possibly even a BIOS setting that is causing issues.
The only way to trouble shoot this is trial and error, and having access to spare parts to eliminate each as an issue.