Ok

Oh, so that's what happens when my computer makes that beep sound. It's overheating! Well, I'll fix that up! Wait, no I won't. I'll wait til I'm done building my computer, and sell this one for some food.

it could also be that your computer is set to shut off at a temperature that is actually of no cause for alarm. Go into your BIOS and check your computer's temperature settings. Shutting off before 70 degrees Celsius is not really necessary.