If you have a recent-model non-retina MacBook Pro, you may have noticed a glassy, high-pitched scraping sound coming from inside the laptop when it warms up. Sometimes, moving the computer will cause the noise. Other times, the noise just happens of its own accord. youtube recording of noise Want to fix it? Take off a few screws... Find the offending part... Remove it! WHAT DID YOU MAKE ME DO?????!!!!! Here's the lowdown: The bottom cover of the MacBook Pro serves as a shield for radiated electromagnetic energy. A great shielding strategy is to find a huge piece of metal, and connect your circuit to that metal wherever possible. The MacBook Pro Unibody enclosure and bottom cover make a terrific shielding system. One of the connectors in this system touches the bottom plate right in the center where it flexes a lot. When the computer heats up, the metal pins in the connector scrape noisily against the cover and chassis. It makes you want to eat your hands. By removing the connector (two easy screws!), you remove one of the grounding connections between the unibody enclosure and the bottom cover. Don't worry: there are plenty of other connections, and they are adequate for the purpose. Result: Quiet, harmonious environment restored.