How to Reset NVRAM on Mac

Unlike regular RAM, which clears every time your Mac powers off, NVRAM retains its contents without power. macOS reads these settings during the earliest stages of startup, before the operating system fully loads. This allows the Mac to apply your preferred display resolution, boot from the correct disk, and set the correct audio volume before you reach the desktop.

Older Macs used a similar technology called PRAM (parameter RAM). While the underlying hardware changed, the concept remains the same. Many Mac users and Apple support articles still refer to "resetting PRAM" interchangeably with resetting NVRAM. The keyboard shortcut and the effect are identical on any Mac that supports the manual reset procedure.

The settings stored in NVRAM are relatively small but critical. A corrupted NVRAM value can cause your Mac to boot from the wrong disk, display at an incorrect resolution, play audio at maximum volume on startup, or report the wrong time zone. Resetting NVRAM restores these values to their factory defaults and lets macOS reconfigure them automatically.

Step 1: Shut down completely. Use the Apple menu and select Shut Down. Wait until the Mac is fully powered off. Do not use restart, because you need to press the key combination before the Mac begins its startup sequence.

Step 2: Power on and hold the key combination. Press the power button, then immediately press and hold all four keys: Option+Command+P+R. You must press them before the gray screen appears. If you see the macOS loading bar, you waited too long. Shut down and try again.

Step 3: Wait for the reset to complete. On Macs with a startup chime, keep holding the keys until you hear the chime a second time, then release. On Macs without a startup chime (2016 and later models), hold the keys for approximately 20 seconds. On T2 chip Macs, hold the keys until the Apple logo appears and disappears for the second time.

After releasing the keys, your Mac will continue starting up normally. You may need to revisit System Settings to reconfigure your display resolution, startup disk, time zone, and sound volume, since these values return to their defaults after a reset.

Apple redesigned the startup process for Apple Silicon. The M-series chip checks NVRAM integrity as part of every boot sequence. If any stored value is corrupted or inconsistent, the system automatically resets it to the default without user intervention. This eliminates the need for the manual reset procedure entirely.

If you experience issues on an Apple Silicon Mac that would traditionally call for an NVRAM reset (wrong display resolution, incorrect startup disk, time zone problems), start by restarting your Mac using the Apple menu. This triggers the automatic NVRAM validation. If the issue persists after a restart, the cause is likely something other than NVRAM corruption.

Apple Silicon Macs use a different method to access startup options. Instead of holding keyboard shortcuts during boot, you shut down the Mac completely, then press and hold the power button until "Loading startup options" appears. From there you can select a different startup disk, enter Recovery Mode, or access other boot options that were previously tied to NVRAM settings on Intel Macs.

Display resolution problems. If your Mac starts up with the wrong resolution, shows a blurry screen, or does not detect an external display correctly, a corrupted NVRAM resolution value may be the cause. Resetting clears the stored resolution and allows macOS to detect and apply the correct setting during the next boot.

Startup disk selection errors. NVRAM stores which disk your Mac should boot from. If macOS cannot find the designated startup disk (for example, after removing a Boot Camp partition or disconnecting an external drive), the Mac may show a flashing question mark folder. Resetting NVRAM lets the Mac rediscover the correct boot volume.

Sound volume and time zone issues. An unexpectedly loud startup chime or audio playing at full volume when you log in can result from a corrupted volume setting in NVRAM. Similarly, a Mac that consistently shows the wrong time zone despite correct settings in System Settings may have a stale NVRAM value overriding the configured time zone.

Kernel panic persistence. NVRAM stores recent kernel panic information. In rare cases, corrupted kernel panic data can interfere with the startup process or cause repeated panics. Resetting NVRAM clears this stored data and gives the Mac a clean starting state.

An NVRAM reset restores settings to their defaults, but it does not guarantee that the underlying issue is resolved. Verifying that your system is performing correctly after the reset requires monitoring key hardware metrics. MoniThor provides this visibility without opening Activity Monitor or running Terminal commands.

Display resolution issues that prompted the reset may be related to GPU performance.MoniThor shows GPU utilization and output statistics so you can confirm the graphics subsystem is operating normally after the reset. If GPU metrics look abnormal, the issue may require further troubleshooting beyond NVRAM.

Battery statistics and CPU thermal readings in MoniThor confirm whether power management returned to normal after the reset. A Mac that was overheating or draining battery rapidly before the NVRAM reset should show improved thermal behavior and power consumption in the menu bar metrics. If these readings remain elevated, an SMC reset or hardware diagnostics may be the next step.

Think of NVRAM as storing preferences that macOS reads at startup. These are settings you could configure manually through System Settings, but NVRAM makes them available before macOS fully loads. When NVRAM becomes corrupted, the symptoms are primarily visual or configuration related: wrong resolution, wrong disk, wrong volume, wrong time zone.

The SMC operates at a lower level, controlling physical hardware behavior. Fan speed, LED indicators, battery charging circuits, power button response, and sleep and wake behavior all run through the SMC. When the SMC encounters issues, symptoms are physical: fans spinning at full speed, Mac not turning on, battery not charging, or unexpected shutdowns. See our Reset SMC on Mac guide for detailed instructions.

If you are unsure which reset to try, start with NVRAM because it is less disruptive and takes only 20 seconds. If the issue involves power, fans, charging, or sleep behavior, proceed to an SMC reset. On Apple Silicon Macs, a simple restart handles both, since NVRAM resets automatically and the SMC equivalent is integrated into the M-series chip.