How to reset PRAM/NVRAM on OS X Mountain Lion?

kreiley

How do you reset the Parameter RAM / Non-Volatile RAM on a Mac running Mountain Lion? I've had a couple start-up crashes this week and want to give it a try before I just reinstall OS X. Thanks!

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jlister
Vote Up (20)

You can zap your PRAM/NVRAM by restarting your machine and pressing Command+Option+P+R. Make sure to hold keys down until it restarts. I would continue to do it until it restarts again, but I'm honestly not sure whether there is any benefit to doing so or if it is an old Mac wives tale.  

lmile61
Vote Up (19)

You need to reinstall the OS and if some important data then difficult to restore after reinstalling.I think there is no another way.

 

jimlynch
Vote Up (15)

This support article from Apple should help:

OS X Mountain Lion: Reset your computer’s PRAM
http://support.apple.com/kb/PH11243?viewlocale=en_US&locale=en_US

"A small amount of your computer’s memory, called “parameter random-access memory” or PRAM, stores certain settings in a location that OS X can access quickly. The particular settings that are stored depend on your type of Mac and the types of devices connected to it. The settings include your designated startup disk, display resolution, speaker volume, and other information.

Note: To print these instructions, open the Help Viewer’s Action pop-up menu (looks like a gear) and choose Print.
Shut down the computer.
Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
Turn on the computer.
Immediately press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
Continue holding the keys down until the computer restarts, and you hear the startup sound for the second time.

Release the keys.
Resetting PRAM may change some system settings and preferences. Use System Preferences to restore your settings."

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