Try and borrow a PSU from a friend to test. A old PSU might work for a while and then when the strain gets to much for it stop.
Think of it like running Prime. You do not run prime for one minute and say OK my system is stable because it passed one minute. No you run prime for quite some time and if you get it right it will not fail any workers. But time has to pass for the error to be found. I think it is the same with older PSU's
Me I change replace my PSU's every two years. Even without problems they are now getting tiered and there will be degradation of the PSU.
So test and find out.
If you wish test your ram using Memetest and run many cycles of the test too.
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