I for one would find it highly unlikely that you would get two faulty boards. Not impossible but unlikely.
Since memory tests OK I would be inclined to invest in a much better
PSU because you simply can't go wrong there in any case.
PSU's are often way underrated as to their importance and it's far better to have too much power than to flirt with just enough just as it isn't wise to buy generic in that instance.
It's the heart of your system and as such you want a strong reliable one.