When and How to Reset Mac SMC (System Management Controller)

Mar 24, 2010 - 28 Comments

sad mac reset the smc Ahhhh my Mac isn’t working! So you’ve tried rebooting, you’ve reset the PRAM, you’ve done it all, but your Mac is still behaving strangely. What next? In certain circumstances, try resetting your Mac’s System Management Controller (SMC). This is sometimes necessary to restore normal lower level system functionality to your Mac, particularly if you’re having these types of problems:

* Issues with your Mac’s cooling fans and fan management: 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

So now that you’ve concluded you need to reset your SMC (Note that the SMC is on Intel Mac’s only), here’s how to do it on MacBook’s, MacBook Pro’s, iMac’s, Mac Mini’s, and Mac Pro’s. Notice that the reset instructions are different for MacBook and MacBook Pro’s if you have an internal or detachable battery.

Reset SMC of a MacBook Air, MacBook Pro Retina, or MacBook Pro’s with an internal non-removable battery:

* Shutdown your MacBook/Pro
* Connect the power adapter to your 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
* Boot your Mac as usual

Reset the SMC of a MacBook Air or Retina MacBook Pro

Reset SMC of an iMac, Mac Pro, Mac Mini:

* 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:

* 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.

Hopefully that will clear up your problems, if not it might be worth a visit to the Apple Store or a certified repair center.

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Posted by: Bill Ellis in Mac OS X, Troubleshooting

28 Comments

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  1. […] When and How to Reset your Mac’s System Management Controller (SMC) – OS X Daily (tags: osx mac troubleshooting) […]

  2. […] If all else fails, try this, which has worked for some individuals: * Reset your Mac’s System Management Controller (SMC) : Shutdown the MacBook/Pro, remove the battery, disconnect the power, hold the Power Key for 15 seconds. Replace the battery, reconnect power, and zap PRAM and wait for 2 chimes before letting the keys go. Check out more information on when and how to reset your SMC. […]

  3. […] the error message anyway, the message was cleared and everything went back to normal after the SMC power management controller was reset. Anytime your Mac has power management type issues it’s worth giving the SMC reset a shot, it […]

  4. […] + Ctrl + Option + PowerButton 3) Пускаш компа. Общо взето, ако нещо не му работи го оправя. […]

  5. Robert Anderson says:

    OS Lion is destroying Mac Book Pro batteries. Not only is battery life diminished by about 50% but the extra load on the battery is killing the battery itself. Apple is doing their best to deny replacing the ruined batteries but at some point the pressure from customers will make them face this issue, or litigation will.

  6. Ali says:

    special thanks my macbook pro was in that bad mode and with your guide all fixed … love your site

  7. […] I’ve gotten in the habit of immediately putting my MacBook Air to sleep by shutting the lid, by far the easiest method if you’re on the go. Typically this works without a hitch, but today the Air didn’t sleep when shut. Because the MacBook Air has no moving hard drive or sleep light, I didn’t notice this until I went to use it again about two hours later when I found the machine to be unusually hot to the touch because it never slept as intended. From there on it became a repeatable occurrence, and while I’m not sure of the cause, the solution was just a matter of resetting the SMC: […]

  8. Rona says:

    Thank you so much. I did lots of searching to find the answer to my problem (fan running, no keyboard or monitor functionality – external keyboard didn’t work either – and you laid out the answer so clearly and simply and it WORKS! MacBook 1,1 Intel Core Duo

  9. Natasha says:

    After searching the Internet forever this is the only thing that worked! Thanks so much!

  10. Required says:

    If following these directions does not work, try powering down, unplugging, then doing the shift, control, option, power thing then restart. Worked for me when the other didn’t.

  11. Emma says:

    so doing this won’t effect the computers hard drive or data at all right? just want to double check before i try anything that i won’t loose any of my information or something like that. thanks!

  12. Omar says:

    This website is awesome :)

  13. Andy says:

    Ok so I have a MacBook (white) and I’ve tried doing this. I’ve had the same problem as the wont sleep thing, but for about a week. Yesterday, I was about to go to the Apple store and try to fix it, but I got it working last minute and didn’t go in. Well, I started getting these restart messages every time my computer did start working, and had to keep doing this until the computer just gets stuck at the white loading screen with a grey spinning wheel under an apple sign(grey) also, this computer has the rounded edges and no, does not have the removable battery. Help!!!!!!!!!

  14. Jonathan says:

    worked for me!
    Fixed my wifi. Macbook is connecting all by herself :)

    thanks

  15. Shally says:

    My mac book pro doesn’t wanna switch on, I have to flush my SMC, please help, it did this once cause of something I plugged in, got it fixed at a hefty price, but they didn’t really change any part so it should be something I can change myself…

  16. JoMO says:

    Thank YOu!!!!!!!!!!!!

  17. David says:

    I’m trying to reset the SMC on my MacBookPro 17″ 2010 because, as many others I’m having all sort of problems since when I updated my system to damn Mavericks!

    How long do I have to hold shift+ctr+opt+power buttons down? I tried to just push them, I tried to hold them down for a little while… how do i understand that the SMC has indeed been reseted? A beep? A light? Any sign at all?

  18. Manfred Abel says:

    Thx a lot for this manual.
    I was running FileVault to save my files, but because I had wrong rights filevault terminates my Mac, so that it freezes and nothing more was working. After a hard reset and after trying to reboot from the recovery it only came the internet recovery option. Nearly on the way to the Apple store. Could be that the hard drive is dead. I read your explanation of the smc reset. I tried, because it was my last chance. Done and rebooted into the recovery section with the harddiskrepair. Checked the harddisk…seems okay, but the rights are wrong. Trying now to fix the issue and maybe then I will have the chance to unlock the data. I will see, because decrypted not really much. Maybe I have a chance. But without your help I will be now at the Apple store and bought me a new hard drive or ship it to the care center. Thx from Germany !!! You saved my day. Trying to get help the whole night without any sleep and now it’s high noon

  19. Stefan says:

    Worked perfect. Aluminum macbook 10.6 with new anker battery.

  20. Andres says:

    I’m having problems with my MacBook Pro-2011, with an SSD and running Lion.
    I reset the SMC twice in the last two weeks because the laptop works fine for a little while after doing it. But after using it for a few days, it gets weird again. It starts with the fans running very high when charging the battery and it could just turn off suddenly at any moment.
    Any ideas? Do I have to keep resetting the SMC once a week?
    Great website, by the way. Thanks!

  21. Peter U says:

    Awesome! My MacBook Pro was booting to black screen. Last time it happened it was a PRAM reset boot that seemed to “fix” it. But this time it was this trick. For people not understanding the instructions, you press those buttons, and yes, there is no feedback!-P but you just press power alone afterwards to reboot. This time no black screen. What is this actually doing?!?!?!!!!!

  22. David McKay-Katsikas says:

    What it’s doing is clearing the cache that stores hardware power settings. Sometimes it can corrupt and cause random hardware issues.

  23. Manav says:

    Thanks so much it worked!

  24. Brent says:

    Worked great for me – reset my battery and saved me from buying a new one.

  25. Tomasas says:

    Thanks a lot, it works for my MacBook A1181 100%!!!!! Thank you!

  26. ross says:

    i have a macbook air, recently got a mini display port to connect to my tv via hdmi. ever since i connected it my tv picture is now flashing on and off but sound stays constant. when i disconnect and try and play my ps3 its still flashing. tv was fine before i tried connecting my mac. I’ve gotten it to work twice but then it stops again. when i try reset smc it works for a couple of seconds then flashes again

  27. Larry Feller says:

    my iMac 24″ mid 2009 last October 2013 would not power up just a black screen & 3 beeps that would repeat after a few seconds. I put it in the box until March 2014 then took it to Apple Store where it powered on to my surprise. It worked until May & the same unable to power up happened. Tried off & on for two months but still a black screen with the beeps. I saw your article yesterday morning & tried it as the power cord had not been plugged in I removed it from the back of the iMac & followed your instructions. It powered right up where it left off back in May. Thank you very much for the info. It took the rest of the day to do all the updates through installation of lattest operating system Yosemite. Again thanks😃

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