How To Reset Your Mac’s SMC & PRAM
Sometimes your Mac will act strange for no apparent reason — lights won’t be working correctly, volume settings will be off, display resolution will change, or a number of other issues that aren’t related to specific apps will pop up. Most of the time, these issues can be solved by closing all of your apps and restarting the computer. Sometimes, though, you’ll need to reset the SMC and PRAM.
The system management controller (SMC) is a chip in your intel-based Mac that’s involved in running a lot of the physical parts of the machine, like LED indicators, keyboards and other peripherals, cooling fans, and power buttons. It also plays a role in the behavior of your hard drive, how your computer behaves in sleep mode, and the power supply.