If the Mac is abnormal, the usual prompt is to try to reset the NVRAM. NVRAM or non-volatile random access memory was called PRAM (parameter RAM) many years ago. NVRAM is a special memory area on the Mac that is used to store data that can be retained even after the Mac is turned off, such as volume settings and screen resolution-this is the information used to maintain settings after the computer is restarted.
Resetting NVRAM (and/or SMC-also known as System Management Controller, which is responsible for power management, discussed here: How to reset SMC on Mac) can resolve issues such as high-speed fans, incorrect connected screen resolution and even It is a Bluetooth problem.
Reset NVRAM on M1 Mac
In November 2020, Apple introduced the first Mac equipped with the M1 chip. With Apple's new system, NVRAM cannot be reset.
Unlike the SMC that no longer exists on the M1 Mac, NVRAM exists but works differently.
The new Mac still has a parameter memory, you can use the terminal command NVRAM to view and change its settings, but there is no longer any command to reset the contents of NVRAM.
According to some sources, including accessory manufacturer Caldigit, and comments on the Apple Support Forum (the statement claims to have talked to Apple Support), when the computer starts from shutdown (that is, not after a normal restart), the M1 processor Will test NVRAM. If there is a problem with the memory, it will automatically reset.
So far, we have not been able to test whether this means that the M1 Mac can "save" the wrongly set NVRAM value. If you use the NVRAM tool to make manual changes, we recommend that you take extra care.
Another way is to start the Mac in recovery mode, start "Terminal" from the "Tools" menu, and enter the following command:, NVRAM -cwe have seen reports that this command may give an error message, but it still works, And the computer will forget, for example, the password of the connected wifi network.
Reset NVRAM on Intel Mac
If your Mac is earlier than November 2020, it may have an Intel processor, so you will need to use this key combination to reset NVRAM.
1. Hold down the following keys: Command, Option (Alt), P and R.
2. Turn on the Mac while holding down these keys.
3. Keep holding down the key until you hear the Mac restart.
4. Listen for a second restart and then release the keys.
In some cases, your Mac will restart normally. In other cases, you may see a progress bar appear. Usually the progress bar will fill up and then the Mac will start. We have seen some cases where the Mac shuts down near the end of the progress bar and then restarts.