Hello,
Sorry i couldn't respond to this thread was having some medical problem. So even after upgrading the PSU didn't fix the problem rite ? I'm not too good in Hardware but I Google around the error you got from Prime95 test most of them says it's fixed by bumping the voltage of RAM a little high maybe upto 1.9V the MemTest seems like it found one error that quiet clear i might be something to do with Hardware components. I agree with CommonTater if it covers warranty i don't see a point you wasting some much time on this issue rather have them fix it for you.
Good Luck,
Captain