How to Reset PRAM on a Mac
Resetting your PRAM is a common troubleshooting technique when a Mac is misbehaving. I’ll cover how to reset PRAM in addition to information about PRAM to help you understand when and why you’d want to reset it.
Resetting the PRAM
You reset the PRAM by rebooting a Mac and then immediately hold down the Command+Option+P+R keys, you will then hear the Mac reboot sound again, signifying your PRAM has been reset. You must hit the key combination before the grey screen appears otherwise it won’t work.
How do you know the PRAM is reset?
The PRAM has been reset only if you hear the Mac reboot sound a total of two times – once for the initial reboot and again when the PRAM has been reset (technically you can keep holding down the key combo and reboot the Mac over and over, but there is no practical reason to do so). You can then let your Mac boot up as usual.
Does resetting PRAM work on all Macs?
Yes, the command combination to rest PRAM has been the same for ages, and it works on all Macs, whether they are Intel or PPC architecture, a MacBook Pro, iMac, or a Mac Mini, or whatever else, the key command is the same and the effect is the same.
What is PRAM?
PRAM stands for Parameter RAM, and it holds assorted information about your Mac so that it functions to your specifications.
In no particular order, here are some things stored in PRAM:
- Startup disk
- Disk caches
- RAM disks
- Virtual Memory (commonly called swap)
- 32-bit addressing
- Video and display information including monitor depth, refresh rate, screen resolution, and number of colors
- Volume for both system startup and speaker
- Time zone information
- Mouse and trackpad scaling and speed information (commonly called mouse acceleration)
- Keyboard repeat rate
- Kernel Panic information
- DVD region settings
- Default system fonts
Because of the information stored in PRAM, if you reset the PRAM you’ll often have to readjust things like your mouse tracking speed, time zone (if it’s not set to an online server), and any non-native resolution that any attached display is running.
When do you want to reset PRAM?
You generally only reset PRAM when troubleshooting something that is directly related to the above listed contents of the parameter RAM, outside of resolving problems or adjusting hardware changes there isn’t much other use for doing so.