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How to Reset NVRAM/PRAM and SMC on macOS
Fix startup, display, sound, and power issues on your Mac by resetting low-level hardware memory and system controller settings.
📋 Before You Begin
- These resets are safe and will not delete your files, applications, or personal settings.
- NVRAM/PRAM stores settings like display resolution, startup disk, time zone, and speaker volume.
- SMC controls power, fans, battery, and keyboard backlighting on Intel-based Macs.
- Apple Silicon Macs (M1, M2, M3, M4) do not have a traditional SMC or NVRAM reset — a restart is sufficient; see Section 4 for details.
- Make sure your Mac is plugged into power if it is a laptop before performing these steps.
Section 1 — When to Use These Resets⌛ ~2 min
NVRAM/PRAM and SMC resets solve a specific class of hardware-level problems. Use them when you experience the following issues:
Reset NVRAM/PRAM when you notice:
- Wrong display resolution or scrambled screen after startup
- Incorrect time zone or system clock
- Wrong startup disk being selected
- Volume or sound settings that keep resetting
- Kernel panic messages at startup
Reset SMC when you notice:
- Fans running at full speed for no reason
- Battery not charging or incorrect battery percentage
- Mac not waking from sleep or not sleeping properly
- Keyboard backlight not responding
- Power button not responding as expected
💡 Tip: Before resetting NVRAM or SMC, try a standard restart first. Many minor issues are resolved with a simple reboot without needing a hardware-level reset.
Section 2 — Reset NVRAM/PRAM (Intel Mac)⌛ ~3 min
NVRAM (Non-Volatile Random-Access Memory) stores small amounts of settings that your Mac needs quickly at startup. This procedure applies to Intel-based Macs only.
- Shut down your Mac completely — go to Apple menu > Shut Down and wait for it to power off fully.
- Locate the following keys on your keyboard: Option + Command + P + R.
- Press the Power button to start your Mac.
- Immediately press and hold Option + Command + P + R all at the same time before the gray startup screen appears.
- Hold the keys for about 20 seconds. On older Macs with a startup chime, release after hearing the chime twice. On newer models, release after the Apple logo appears and disappears twice.
- Release the keys and allow your Mac to finish starting up normally.
⚠️ Warning: You must press the key combination before the gray startup screen appears — timing is critical. If you see the login window, the reset did not occur and you need to restart and try again.
💡 Tip: After an NVRAM reset, some settings like speaker volume, display resolution, and startup disk selection may revert to defaults — check System Settings to restore your preferences.
Section 3 — Reset SMC (Intel Mac)⌛ ~5 min
The System Management Controller (SMC) handles low-level hardware functions. The reset procedure differs depending on whether your Mac has a removable battery.
MacBook with non-removable battery (most modern MacBooks):
- Shut down your MacBook completely.
- Connect the power adapter (MagSafe or USB-C charger).
- On the built-in keyboard, press Shift + Control + Option on the left side, then press and hold the Power button at the same time.
- Hold all four keys for 10 seconds.
- Release all keys, then press the Power button again to start your Mac.
Mac mini, iMac, Mac Pro, or Mac Pro Tower:
- Shut down the Mac completely.
- Unplug the power cord from the back of the Mac.
- Wait 15 seconds.
- Plug the power cord back in.
- Wait 5 more seconds, then press the Power button to turn the Mac on.
⚠️ Warning: Use only the built-in keyboard for the SMC reset key combination — an external USB or Bluetooth keyboard will not work for this procedure.
Section 4 — Apple Silicon Macs (M1/M2/M3/M4)⌛ ~2 min
Apple Silicon Macs use a fundamentally different architecture — they do not have a separate NVRAM chip or SMC component that can be manually reset using key combinations.
- To identify your chip, go to Apple menu > About This Mac — look for M1, M2, M3, or M4 under the chip line.
- If you have an Apple Silicon chip, a standard Restart or Shut Down and power back on accomplishes the equivalent of an NVRAM or SMC reset.
- Go to Apple menu > Restart and allow your Mac to restart completely.
- If the issue persists after a restart, go to Apple menu > Shut Down, wait 30 seconds, then press the Power button to restart.
- If the issue still persists, contact IT support — further diagnostics or a macOS reinstall may be needed.
💡 Tip: Not sure which chip you have? Go to Apple menu > About This Mac. If it lists Intel Core under Processor, use the NVRAM and SMC steps above. If it shows Apple M1 (or later), use the steps in this section.
Section 5 — Verify Settings After Reset⌛ ~3 min
After an NVRAM/PRAM reset, several system preferences may revert to defaults. Check the following settings and restore them if needed:
- Go to Apple menu > System Settings > General > Startup Disk and confirm the correct startup disk is selected.
- Go to System Settings > General > Date & Time and verify your time zone is set correctly.
- Go to System Settings > Sound and check that your output volume and default sound device are correct.
- Go to System Settings > Displays and confirm your display resolution and arrangement are as expected.
- If you use FileVault encryption, verify it is still enabled under System Settings > Privacy & Security > FileVault.
- Test the original problem that prompted the reset to confirm it is resolved.
💡 Tip: If the issue that prompted the reset is not resolved after completing both NVRAM and SMC resets, it may indicate a deeper hardware or software problem — contact IT support for further assistance.
🙋 Still Need Help?
If resetting NVRAM, PRAM, or SMC did not resolve your issue, our IT team can perform in-depth hardware diagnostics on your Mac.
📞 Phone: (918) 540-6099
🚶 Walk-in: IT Department, Library Administration, 2nd Floor, Room 216
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