PRAM/NVRAM reset resolves Mac settings abnormalities, startup issues, or sound display failures. PRAM is the way to set up early Mac storage systems, while NVRAM is an alternative to subsequent models, and data is maintained by relying on the motherboard battery when shutting down. When boot disk recognition fails, invalid settings, confusing resolution or time errors occur, PRAM/NVRAM may need to be reset. The basis for judgment includes: displaying the question mark icon on the power supply, rebooting and restoring the default after adjusting the settings, abnormal external monitors, and frequent system time errors. Different models of Mac operate as follows: 1. Apple Intel chip Mac: Press and hold Option Command PR after shutting down for about 20 seconds; 2. Apple M1 or updated chip Mac: hold the same key combination after shutting down until the Apple Logo appears for the second time; 3. Old Mac (2008 years ago): Remove the motherboard PRAM battery for a few seconds or use terminal commands. After resetting, the settings such as volume, brightness, boot disk will be restored to default. It is recommended to recheck the configuration.

The Mac's PRAM (parameter memory) or NVRAM (nonvolatile random access memory) is responsible for saving some key system settings, such as volume, monitor resolution, boot disk selection, etc. If you encounter system settings abnormalities, startup problems, or sound display related failures, resetting PRAM/NVRAM is often an effective solution.

What are PRAM and NVRAM?

PRAM (Parameter RAM) is a storage area used by early Macs to save system settings. Later models used NVRAM (Non-Volatile RAM). Although the names are different, the functions are similar. It can also retain data when the Mac is shut down, relying on the small battery on the motherboard (similar to CMOS batteries). When this part of the data is wrong, it may cause some strange problems, such as:

• The boot disk cannot be recognized when booting
• Don't remember the volume or screen brightness settings
• Time display error

At this time, you can try resetting PRAM/NVRAM.

How to determine whether you need to reset PRAM/NVRAM?

Not all problems can be solved by this, but you can try it in the following situations:

• A question mark icon appears when starting up the Mac (start disk cannot be found)
• The settings will not take effect after adjustment, restart and return to default
• The external monitor settings are chaotic and the resolution is incorrect
• Frequent system time errors

If you haven't operated these settings before, but suddenly the above problem occurs, it may be that there is something wrong with PRAM/NVRAM.

How to reset PRAM/NVRAM for different models of Macs

Apple Intel chip Mac (with T2 chip also applies)

1. Turn off the Mac.
2. Press the power button, and then press and hold these four keys immediately : Option Command PR
3. Keep holding these keys for about 20 seconds , during which you may see the Apple logo or progress bar.
4. Release the button to enable the Mac.

Tip: Some users mistakenly think that they just need to hold down the key until the Apple Logo appears and let go. In fact, it is recommended to persist for a few more seconds to ensure the reset is complete.

Apple M1 or Mac with newer chips (Apple Silicon)

This type of Mac does not have PRAM in the traditional sense, but the way to reset NVRAM is similar:

1. Completely shut down.
2. After waiting for a few seconds, press the Power key and immediately hold the Option Command PR key on the keyboard.
3. Keep holding it for about 20 seconds until you see the Apple Logo appear for the second time, which means that it has been restarted.
4. Let go and start normally.

Older Mac (before 2008, using PRAM)

If you are using a very old Mac (such as PowerPC architecture), the steps are slightly different:

1. Turn off the computer.
2. Open the chassis (if convenient), find the PRAM battery (usually a button battery) on the motherboard.
3. Remove the battery for about 5–10 seconds and then reinstall it.
4. Or use the terminal command sudo nvram -c (provided that you can enter the system).

Note: Most Macs do not need to be disassembled now. Unless you are sure it is a motherboard problem, it is not recommended to operate the hardware by yourself.

What should I pay attention to after resetting?

After PRAM/NVRAM is cleared, some personalized settings will be reset, such as:

• Volume and brightness return to default
• Switch back to system defaults
• Time format and language may also be restored to factory settings

So after resetting, you need to recheck whether these settings are in line with your habits. In addition, if you set up multiple boot systems (such as dual systems), you may need to re-specify the default boot disk.

Basically that's it. Operations are not complicated, but they are easily overlooked or misoperated. If you encounter the problem of "can't remember" the system settings or the startup exception, you might as well try this method first.

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