When it comes to computers, heat is a bad thing. An overheated CPU will shut down, which sucks for obvious reasons. Operating at high temps can also lead to a shorter lifespan, which is equally bad, if not quite as obvious. Fortunately, the aluminum unibodies of Apple’s MacBooks are pretty good at dissipating heat. But that doesn’t stop snake-oil salesmen from trying to convince you that your trusty MacBook is really a fiery inferno just a few clock cycles away from melting into an expensive puddle of goo.