Max Headroom 
The System Management Controller, or SMC, is a critical low-level component on Mac hardware. The SMC controls and managements system hardware for power consumption, battery charging and battery function, thermal activity and fan activity, LED lighting for keyboards and displays, GPU functionality with video mode changes and video output, sleep and wake, and other core hardware functionality on a Mac.
When & Why Reset SMC on a Mac?
Typically, an SMC reset helps to resolve many power and hardware related issues that are otherwise unresponsive to troubleshooting techniques. Resetting a Mac SMC is particularly effective if you’re having the following types of problems:
* Issues with your Mac cooling fans and fan management: the fans run constantly at high speed, fans run high despite low CPU usage and adequate ventilation, fans not working at all, etc
* Power management and battery problems: Mac isn’t turning on, sleep isn’t working, random shutdowns and reboots, battery isn’t charging, Mac won’t wake from sleep, etc
* Light problems and improper lighting management: battery indicator lights aren’t working, display backlighting isn’t adjusting to ambient light changes, keyboard backlights not working, etc
* Video and external displays not working: display brightness functionality not working properly, target video mode isn’t working properly, external display isn’t working, etc
* General performance and functionality problems: abnormally sluggish behavior despite no CPU or disk usage, external ports not working, airport & bluetooth aren’t showing up, external devices are not being found, etc
If those type of issues describe the problem encountered on the Mac and you have concluded that you need to reset your SMC, we will show you how to do it on any MacBook, MacBook Pro, MacBook Pro with Retina display, iMac, Mac Mini, and Mac Pro. Do notice that the System Management Controller reset instructions are different for some Macs, including MacBook and MacBook Pro’s if the machine has a T2 security chip, as well as an internal battery versus a detachable battery, and additionally the procedure is different for some newer desktop Macs than older ones, and different than Mac laptops.
How to Reset SMC on Newer T2 MacBook Air, MacBook Pro with Touch Bar
On the latest model Mac laptops with security chips, Touch ID, and Touch Bar, resetting the SMC is performed as follows:
- Shut down the Mac
- On the laptop keyboard, press and hold the following keys, this sometimes causes the Mac to turn on:
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- Control on the left side of keyboard
- Option / Alt on the left side of keyboard
- Shift on the right side of the keyboard
- Continue holding those keys for 7 seconds, then in addition also press and hold the power button – if the Mac is on, it will turn off as you hold the keys
- Continue holding all four keys for another 7 seconds, then release them concurrently
- Wait 3-4 seconds, then press the Power button again to turn on the Mac
The Mac will now boot as usual with the SMC freshly having been reset.
Reset SMC of a MacBook Air, MacBook Pro Retina, or MacBook Pro’s with an internal non-removable battery
This is how to reset SMC on Mac laptops with a non-removable battery:
- Shutdown your MacBook Air / MacBook Pro
- Connect the power adapter to the Mac
- On the MacBook / Pro’s keyboard, hold down the Shift+Control+Option keys and the Power button at the same time
- Release all keys and the power button at the same time – the little light on the MagSafe adapter may change colors briefly to indicate the SMC has reset
- Boot your Mac as usual
Here’s the key sequence to hold down:
Do keep in mind that by resetting the SMC you will lose power specific settings, like the time it takes to sleep a Mac and other customizations to power settings. No big deal, but if you have made many changes to your hardware behavior you will want to adjust stuff like sleep behavior again.
The boot time after resetting a machines SMC can be a bit longer than usual, that is normal.
How to Reset SMC on Newer iMac, iMac Pro, Mac Pro, Mac mini with T2 Chip
Resetting SMC is different for non-portable Macs, but it’s still easy enough and the problems it addresses are the same. For newer Mac desktop models with a security chip (t2 or otherwise) you can reset SMC as follows:
- Shut down iMac, then unplug the power cord
- Wait 15 seconds, then plug the power cord back in
- Wait 5 seconds, then press the power button to turn on your Mac
Reset SMC of an older iMac, Mac Pro, Mac Mini
On older model desktop Macs without security chips, here is how you reset the System Management Controller:
- Shut down your Mac
- Disconnect the power cord
- Press and hold the Mac’s power button for 5 seconds
- Release the button
- Reattach the power cables and boot the Mac as usual
Reset the SMC of a MacBook or MacBook Pro’s with detachable batteries
Older MacBook laptops, indicated by having a removable battery, can reset SMC with the following approach:
- Shutdown the MacBook/Pro and remove the battery
- Disconnect the power adapter, hold the Power Key for 10 seconds
- Release the power key and reconnect your battery and power adapter
- Turn your Mac on
- Let boot as usual
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Now that your Mac SMC has been reset, the hardware issue you were encountering should be resolved, unless there is a greater problem or a different issue that needs to be troubleshooted separately. Sometimes resetting the Macs PRAM can be effective too, though there are times when further action is necessary as well. Do note that only Intel Macs have an SMC controller.
