How to reset NVRAM / PRAM of MAC ?

Resetting the NVRAM (Nonvolatile Random-Access Memory) or PRAM (Parameter RAM) on a Mac can resolve issues related to system settings, such as boot problems, display settings, audio issues, or power-related quirks.

NVRAM/PRAM stores low-level settings like startup disk selection, screen resolution, speaker volume, and time zone, and resetting it clears corrupted or outdated configurations without affecting your data or macOS installation.

Below is a detailed step-by-step guide to reset NVRAM/PRAM on different Mac models, tailored to your macOS context, along with why and when to do it.

A video shows How to reset NVRAM / PRAM of MAC ?

Why Reset NVRAM/PRAM?

NVRAM/PRAM holds settings critical to Mac startup and basic hardware functions, including:

Startup: Boot disk selection, startup chime (older Macs).
Display: Screen resolution, refresh rate, brightness.
Audio: Speaker volume, mute settings.
System: Time zone, double-click speed, recent kernel panic info.
Power/Boot: Sleep/wake behavior, boot mode (e.g., Safe Mode flags).

Resetting NVRAM/PRAM fixes issues caused by corrupted settings, often seen in:

Mac boots to a question mark folder or wrong startup disk.
Display resolution stuck or incorrect (e.g., blurry external monitor).
No sound from speakers or volume keys unresponsive.
Time zone or clock incorrect after restarts.
Slow boot times or failure to wake from sleep.
USB or peripheral issues (e.g., your corrupted USB from prior questions) tied to boot settings.

When to Reset:

After basic troubleshooting (e.g., restart, check cables, update macOS to Sequoia 15.4).
When boot, display, or audio issues persist.
Before or after an SMC reset (from your recent question) for power-related problems.
If installing macOS Sequoia via USB (your earlier query) fails with boot errors.

Note: Resetting NVRAM/PRAM is safe—it doesn’t delete files, apps, or macOS settings like Wi-Fi passwords or user accounts.

How to Reset NVRAM/PRAM on a Mac

The process differs slightly between Intel-based Macs and Apple Silicon (M1/M2/M3/M4) Macs. Apple Silicon Macs automatically manage NVRAM resets in some cases, but manual steps can still help.

Step 1: Identify Your Mac Model

Check Model:
Go to Apple menu () > About This Mac.
Examples:
- Intel: MacBook Pro (2019, Intel Core i9).
- Apple Silicon: MacBook Air (2024, M3).
Or in Terminal: system_profiler SPHardwareDataType
- Look for “Model Name” and “Chip” (e.g., Intel Core i7 or Apple M4).
Why It Matters: Intel Macs use a specific key combo; Apple Silicon Macs simplify or automate the process.

Step 2: Save Work and Shut Down

Close Apps: Save open files (e.g., recovered USB data from your prior question).
Shut Down:
Apple menu > Shut Down > Wait 30 seconds until fully off.
If unresponsive, hold the power button for 10 seconds (Intel) or 20 seconds (Apple Silicon).

Step 3: Reset NVRAM/PRAM

Intel-Based Macs (Pre-2020)

Models: MacBook Pro (2010-2020), MacBook Air (2010-2020), iMac (2007-2020), Mac mini (2010-2018).
Steps:

Turn off the Mac completely.
Press the power button to start it.
Immediately press and hold these keys together: Command (⌘) + Option (⌥) + P + R.
- Hold for at least 20 seconds or until one of these occurs:
- You hear a second startup chime (on Macs with chimes, pre-2016).
- The Apple logo appears and disappears twice (newer Intel Macs).
Release the keys and let the Mac boot normally.

What Happens:
NVRAM clears, resetting settings to defaults (e.g., startup disk reverts to internal drive).
You may need to reselect time zone or resolution post-boot.

Apple Silicon Macs (M1, M2, M3, M4: 2020-2025)

Models: MacBook Air (2020-2024), MacBook Pro (2021-2024), Mac mini (2023), iMac (2021+), Mac Studio, Mac Pro (2023).
Steps:
Automatic Reset: Apple Silicon Macs reset NVRAM-like settings automatically during a normal reboot in many cases, so a manual reset may not be needed.
Manual Check via Startup Options:
1. Shut down completely (Apple menu > Shut Down).
2. Press and hold the power button until “Loading startup options” appears (~10 seconds).
3. Select your startup disk (e.g., “Macintosh HD”) > Click Continue.
4. If issues persist, boot to Recovery to clear settings:
- Hold power button again, select Options > Continue.
- In Recovery, go to Utilities > Terminal.
- Run:
  nvram -c
- Restart: reboot.
Why: Apple Silicon integrates NVRAM into the SoC, managed by macOS. Manual resets are rarely needed, but Recovery ensures a clean slate.

Special Case: Macs with T2 Chip (Intel, 2018-2020)

Models: MacBook Pro (2018-2020), MacBook Air (2018-2020), iMac (2020), Mac mini (2018).
Steps: Same as Intel Macs:

Shut down.
Press power button, then hold Command + Option + P + R for 20 seconds.
Release after the second logo or chime.

Note: T2 Macs may require an SMC reset first (per your prior question) if power issues overlap.

Step 4: Verify the Fix

Test Symptoms:
Boot: Does it start to the correct disk? (System Settings > General > Startup Disk to confirm).
Display: Check resolution (System Settings > Displays—should match native, e.g., 2560×1600 for MacBook Pro).
Audio: Test speakers (System Settings > Sound > Output—play a sound).
Time Zone: Verify (System Settings > General > Date & Time).
USB/Peripherals: Plug in a USB (e.g., your Sequoia installer USB) to check recognition.
Success: If the issue (e.g., no sound, wrong disk) is resolved, you’re done.
Failure: Try additional steps below.

Step 5: Additional Troubleshooting

Repeat Reset:
If no change, repeat the NVRAM reset—occasionally needs multiple attempts.
Ensure keys are pressed immediately after power (within 1-2 seconds).
SMC Reset (Complementary):
If power-related (e.g., charging, sleep issues), reset SMC (see your prior question’s answer).
Example: For Intel MacBook, hold Shift + Control + Option + power for 10 seconds.
Safe Mode:
Intel: Restart, hold Shift until login.
Apple Silicon: Hold power button, select volume, hold Shift, click Continue in Safe Mode.
Why: Clears software conflicts affecting boot or settings.
Run Apple Diagnostics:
Intel: Restart, hold D until diagnostics start.
Apple Silicon: Hold power button, select Options > Diagnostics.
Why: Detects hardware issues (e.g., logic board) impacting NVRAM.
Check macOS:
Update to the latest version (System Settings > General > Software Update, e.g., Sequoia 15.4).
Why: Fixes firmware bugs causing NVRAM corruption.

Step 6: Reconfigure Settings (If Needed)

Post-Reset Changes:
Startup Disk: Reselect if it defaults to another volume (System Settings > General > Startup Disk).
Time Zone: Reset if incorrect (System Settings > General > Date & Time).
Display/Sound: Adjust resolution or volume if reset to defaults.
Test USB (Context): If resetting due to USB issues (e.g., your corrupted USB or Sequoia installer), reinsert and check:

  diskutil list

Ensure it mounts (e.g., /dev/disk3).

Step 7: Contact Apple Support (If Unresolved)

When: Persistent issues (e.g., repeated boot failures, no audio).
How:
Visit support.apple.com or book a Genius Bar appointment.
Share diagnostics results for faster service.
Warranty: Check Settings > General > About > Coverage.
Cost: Logic board repairs (if NVRAM-related) ~$300-$700 out of warranty; free if covered.

Sources: Based on Apple’s support docs (support.apple.com/ens), MacRumors, and community guides, verified for macOS Sequoia and 2025 models.