|If the following:|
Your CPU heat sink is free from accumulated dust. AND
Your heat sink/fan is positively properly seated. AND
Your fan is spinning at a reasonably fast RPM.
THEN you might have a bad memory module. In this case, use Memtest to test your memory. If it fails and you have more than one module, retest with only one module at a time to see which is bad and replace accordingly. If it will not even load, or crashes, also try again with one at a time, if the same problem separately with 2 or more, then look elsewhere for your problem.
You have to be a little bit crazy to keep you from going insane.
If all else fails, read instructions.