What are NVRAM and PRAM? Problems, solutions, and optimization
As a Mac owner, you probably find it somewhat embarrassing to admit that every now and then, this seemingly perfect piece of machinery stalls, freezes, chokes, and pulls all sorts of other tricks that are supposed to be reserved for the Windows realm. There is nothing to be embarrassed about, though: your actions definitely make a contribution to the reasons for such mishaps, but they aren’t more than a final push that triggers an unfortunate chain of events.
In this series of articles titled “Fix your Mac yourself,” we shall explore the assorted components of your favorite machine, software and hardware, that can give you trouble in certain circumstances. The exploration, as you understand, won’t stop at describing the predicaments but will suggest some immediate solutions and ways to prevent such unpleasant situations in the future. And the “yourself” part of the title means that the said solutions and ways don’t involve a visit to a service shop. So, first up are NVRAM and PRAM.
What are NVRAM and PRAM?
NVRAM stands for Non-Volatile Random-Access Memory. “Non-volatile” here means this storage keeps the data recorded even without any power supply, as opposed to other types of RAM that “forget” everything in the absence of electricity. Being as fast as the regular types of random-access memory, NVRAM is especially useful for storing critical system data, settings, or calibration information that must survive power failures and persist through reboots. Moreover, the module itself has no moving parts, which ensures exceptionally long service life.
PRAM means Parameter RAM, and it is a legacy term nowadays. Historically, PRAM was a specific type of NVRAM in Apple Macintosh computers, a battery-powered portion of RAM that kept assorted system settings. Over time, its workload was transferred to NVRAM chips or firmware, but the term PRAM remains in use.
For the inquiring minds: outside the Apple ecosystem, PRAM also stands for Parallel Random Access Machine. It is a theoretical model in computer science for parallel computation that has many processors sharing a global memory with random access.
Symptoms of issues related to NVRAM/PRAM
How do you know there’s something wrong with the data stored in your Mac’s NVRAM/PRAM? Here are some telltale signs:
- unusual behavior of keyboard or mouse;
- faulty operation of volume control;
- incorrect time or date;
- screen resolution changes you did not order;
- gray screen after booting or a question mark icon shown during startup;
- general system slowness, freezing, and unresponsive apps;
- troubled sleep mode activation and persistent backlight;
- startup disk selection issues (Mac booting from the wrong disk or failing to remember startup preferences);
- error messages related to NVRAM access or permissions, such as “iokit/common Not Permitted.”
As you understand, such trouble stems from corruption of system settings data in NVRAM/PRAM.
How to fix issues associated with NVRAM/PRAM
Basically, the only surefire way to fix any problem arising from a crippled NVRAM/PRAM storage is to reset it.
How to reset NVRAM/PRAM in an Intel-based Mac
- Shut down your Mac.
- Turn it back on and simultaneously press Option (⌥), Command (⌘), P, and R right away.
- Hold the keys for about 20 seconds, and when the Mac plays the startup sound, release after the second chime. If your Mac has a T2 security chip, release the keys after the Apple logo appears and disappears twice.
- Your Mac will restart in the process, it is normal.
- After startup, you may have to reconfigure some settings like volume, display resolution, or startup disk.
How to reset NVRAM/PRAM in an Apple silicon Mac
Unlike Intel Macs, those powered by Apple silicon don’t require the sequence described above. A simple switch-off-switch-on forces the system to check and reset NVRAM if needed.
You can also reset NVRAM via Terminal: launch it, and run the `sudo nvram -c` command, followed by a reboot. Please note that you may be required to enter the password, and your Mac may boot into recovery mode once to decrypt the SSD.
What are the reasons behind NVRAM/PRAM-related issues?
The common reasons for corruption of data in NVRAM/PRAM are:
- changes made manually using the Terminal;
- bugs in macOS;
- power problems, faulty SMC (System Management Controller);
- conflicting peripherals;
- restrictions in SIP (System Integrity Protection).
The measures to prevent NVRAM/PRAM-related issues stem from the said problems: don’t mess with the NVRAM data using the Terminal unless you know what you are doing, update the OS a couple weeks after its release (not earlier), run Apple Diagnostics (hold D during startup) to rule out hardware issues, unplug peripherals and reboot your Mac, and check SIP settings.
If resetting NVRAM/PRAM temporarily fixes the problem but issues recur frequently, it might indicate a hardware problem such as a failing NVRAM battery (especially in older Macs) or other hardware faults. In this case, it’s best to seek assistance from professionals.
In case you are looking for more general purpose system optimization software for your Mac, browse the Mac.Informer's catalog section storing such programs:
