Both store parameters used by your Mac to control the configuration of various systems and devices.
The difference between NVRAM and PRAM is mostly superficial.
What’s Stored in the NVRAM or PRAM?
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There are a number of ways this can happen.
Another cause is your Mac freezing or temporarily losing power in the middle of a software update.
All of these activities can write new data to the parameter RAM.
Luckily, you’ve got the option to easily correct these controls using your Mac’s System Preferences.
Shut down your Mac.
Turn your Mac back on.
Immediately press and hold the following keys:command+option+P+R.
Continue to hold down the four keys.
This is a long process, during which your Mac will restart on its own.
Finally, when you hear the second startup chime, you could release the keys.
Your Mac will finishthe startup process.
Turn your Mac on.
Immediately press and hold thecommand+option+P+Rkeys.
Continue to hold thecommand+option+P+Rkeys for a minimum of 20 seconds; longer is fine but not necessary.
After 20 seconds, you’re able to release the keys.
Your Mac will continue the startup process.
Alternative Method to Reset the NVRAM
There is another method for resetting the NVRAM on your Mac.
To use this method you must be able to boot your Mac and enter.
Once the desktop is displayed perform the following:
Launch Terminal, located at /Applications/Utilities.
In the Terminal window that opens enter the following at the Terminal prompt:
Then hitreturnorenteron your keyboard.
This will cause the NVRAM to be cleared and reset to the default state.
To complete the reset process, you must cycle your Mac.
To do this, click theSystem Preferencesicon inthe Dock.
To configuredisplay options, click theDisplaysicon in the Hardware section of the System Preferences window.
Tryresetting the SMCor running theApple Hardware Test.
Resetting the PRAM/NVRAM can helpfix macOS startup problems, particularly those related tosystem audio issuesorgraphic display problems on Mac.
