macOS SMC Reset — What It Is & When to Do It

What Does This Error Mean?

The SMC (System Management Controller) is a chip inside your Mac that controls power, fans, sleep, and the battery. When it gets into a confused state, you get strange symptoms — fans running at full speed, Mac not waking from sleep, unexpected shutdowns, or the power button not responding. Resetting the SMC clears its stored state and lets it start fresh. This is a safe procedure that does not delete any files or settings.

Affected Models

MacBook Air (Intel)
MacBook Pro (Intel)
Mac mini (Intel)
iMac (Intel)
Mac Pro (Intel)

Common Causes

Mac fails to wake from sleep or takes an unusually long time to wake
Fans run at full speed constantly even when the Mac is idle or cool
Mac shuts down unexpectedly under normal load
Battery not charging even when the power adapter is connected and the MagSafe/USB-C light is on
Keyboard backlight, display brightness, or other power-related features behave erratically

How to Fix It

First, check if your Mac has Apple Silicon (M1, M2, M3) or Intel. Click the Apple menu > About This Mac. If the chip says 'Apple M1' or similar, skip to step 5. Apple Silicon Macs do not use the same SMC reset procedure.

The SMC reset instructions differ by Mac model. Using the wrong procedure will not harm anything, but it will also not work.
For MacBook with a non-removable battery (most models since 2009): Shut down the Mac. Hold Shift + Control + Option on the left side of the keyboard, then press the Power button at the same time. Hold all four keys for 10 seconds, then release. Press Power to turn the Mac on.

You will not see any visible confirmation that the SMC was reset. This is normal — the Mac will just turn on as usual.
For desktop Macs (iMac, Mac mini, Mac Pro): Shut down the Mac. Unplug the power cord. Wait 15 seconds. Plug the power cord back in. Wait 5 seconds. Press the Power button to turn the Mac on.

Removing power for 15 seconds completely discharges the SMC capacitors, forcing it to reset its state.
For older MacBooks with a removable battery: Shut down the Mac. Remove the battery. Hold the Power button for 5 seconds. Reinsert the battery. Press Power to turn on.

MacBooks with removable batteries have not been sold since around 2012, so this applies only to older hardware.
For Apple Silicon Macs (M1, M2, M3): A full shutdown and restart handles most issues the SMC reset fixed on Intel Macs. Go to Apple menu > Shut Down, wait 30 seconds, then power on. If issues persist, run Apple Diagnostics: hold the Power button at startup until you see startup options, then hold Command + D.

Apple Silicon integrates the power management functions differently, so a true SMC reset is not available or necessary on these models.

When to Call a Professional

If an SMC reset does not fix the symptoms listed above, the underlying hardware component may actually be failing. A Mac technician can run Apple Diagnostics to check the battery, fans, and power management hardware. For Apple Silicon Macs (M1 and later), the SMC is integrated differently and most issues are resolved by a simple restart rather than a separate reset procedure.

Frequently Asked Questions

Will an SMC reset delete my files or settings?

No. An SMC reset only clears the internal state of the power management chip. It does not touch your files, applications, preferences, or any data stored on the drive. Think of it like clearing the memory of a tiny specialized chip — not the main storage of the computer. Your Mac will boot and look exactly the same as before the reset.

My Mac fans are running full blast all the time. Will SMC reset fix it?

Possibly. The SMC controls fan speed based on temperature sensor readings. If the SMC gets stuck in a state where it thinks the Mac is overheating, it will run fans at full speed even when temperatures are normal. An SMC reset clears this state. If the fans return to full blast shortly after the reset, the Mac may actually be running hot — in that case, check for background processes using CPU (open Activity Monitor and sort by CPU usage).

How do I know if the SMC reset worked?

There is no confirmation message. The best way to tell is whether the symptom that prompted the reset has gone away. For example, if the fan was running at full speed, check after the reset whether it has returned to a normal, quiet level. For battery charging issues, check whether the MagSafe or USB-C indicator lights work correctly. If the symptoms return after a few days, repeat the reset and also run Apple Diagnostics to check for hardware faults.