I hate to muddy the waters by not directly answering whether or not it is a bad CPU, it could be, but I have seen the symptoms you describe on both laptops and desktops with faulty power supplies. A faulty PSU can cause voltage variances in CPU power, which can trigger intermittent diagnostic test failures, as well as system freezes. If you have a spare known-good PSU, I would try swapping it and rerunning the tests. If the results are the same, you can have a bit more confidence in the CPU being at fault.