Cleaning out the gremlins: Resetting your Mac’s NVRAM and SMC

If you’re a long-time Mac Tips reader, you might know that your computer stores files in one of two ways. The first is long-term memory, where your data lives on a permanent basis; this is your hard drive or solid state drive, the thing you back up (hopefully!) The other is a form of faster, short term storage, called RAM, that your computer uses to speed things up.

What you might not know is that there are a couple other small forms of storage your computer uses to handle minor system tasks. It’s relatively rare that you’ll have a problem with these, but if your computer is acting up in some way, resetting them is a quick and easy step that might just solve your problem.

If your computer is taking a long time to start up, has the wrong screen resolution, or you have problems with the sound, the culprit may be the NVRAM, a small piece of battery-powered memory that keeps track of things like your computer’s time zone, startup disk, and so forth.

To reset your NVRAM, simply shut your machine down, then press the power button. As soon as you hear the startup chime, hold down the keys Command-Option-P-R until you hear a second startup chime, then let go. (You use the P and R keys because Macs used to use “Parameter RAM” instead of Non-Volatile RAM.)

If on the other hand you’re having problems with loud fans, slow performance, battery issues or sleeping and waking up, it’s more likely to be an issue with your SMC, or System Management Controller. Resetting this is a little more involved and the steps you have to take after shutting down depend on your type of Mac.

  • Desktops (iMac, Mac mini, etc.) – unplug the power cable for 15 seconds, plug it back in, wait 5 seconds and turn it back on.
  • MacBooks with built-in batteries – plug your Mac into power. Press and hold the Shift, Option & Control keys on the left side, then press the power button. Then let go and turn the Mac on again with just the Power button.
  • MacBooks with removable batteries – Unplug the Mac and remove the battery. Press the Power button and hold for 5 seconds, then let go, put the battery and power cord back in, and start the Mac up normally.
If you’re having troubles like these, give these simple resets a shot and you might just solve the problem. If not, you know we’re always here to help!

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