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Sometimes your Mac will act strange for no apparent reason — lights won’t be working correctly, volume settings will be off, display resolution will change, or a number of other issues that aren’t related to specific apps Recognizing Danger: 5 Warning Signs Showing Your Mac Has A Problem Recognizing Danger: 5 Warning Signs Showing Your Mac Has A Problem It's safe to say that the Apple Macintosh computer is a great piece of hardware with a fantastic operating system, but it's definitely not impervious to errors. Sometimes it acts funny, and because continuing on... Read More will pop up. Most of the time, these issues can be solved by closing all of your apps and restarting the computer. Sometimes, though, you’ll need to reset the SMC and PRAM.

What Are SMC and PRAM?

The system management controller (SMC) is a chip in your intel-based Mac that’s involved in running a lot of the physical parts of the machine, like LED indicators, keyboards and other peripherals, cooling fans, and power buttons. It also plays a role in the behavior of your hard drive, how your computer behaves in sleep mode, and the power supply.

mac-pro-smc-board

Parameter random access memory (PRAM) holds information about the configuration of your computer, including things like the date and time, as well as desktop, volume , mouse, and other control settings. It’s powered by a small battery, so these settings don’t get lost every time you turn your computer off.

When Should You Reset the SMC or PRAM?

Most of the time, if you have a problem that requires resetting the SMC or PRAM, your Mac will just be acting strange. It will probably turn on and run the apps you need it to, but some functions will just be wonky. For example, if your SMC isn’t working correctly, you could experience one or more of the following:

If there’s an issue with your PRAM, you’ll see problems like these:

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macbook-pro-boot-error

  • Volume doesn’t respond properly
  • The boot volume isn’t set (you’ll see a question mark before your computer boots up)
  • Strange mouse scrolling and clicking speeds
  • Keyboard not responding normally
  • The time zone or clock changes or won’t change
  • Display resolution changes or won’t change
  • AirPort problems
  • Your computer shuts down slowly

Resetting the SMC and PRAM is the first step toward solving a wide variety of problems, so if your computer just seems a bit off and restarting it doesn’t fix the problem, you should consider resetting one or both of these.

Resetting SMC

Before resetting either the SMC or PRAM, it’s a good idea to close all applications and reboot your computer to see if that fixes the problem. Also, when you restart your computer after resetting either of these, it may take a little while longer to boot up. Apps might take a bit longer to get started too, but they’ll get back to normal speed quickly.

Resetting the SMC is done in different ways depending on the type of computer you have.

MacBook With Removable Battery

  1. Shut down the computer.
  2. Unplug the power adapter.
  3. Remove the battery.
  4. Press and hold the power button for five seconds.
  5. Replace the battery.
  6. Plug in the power adapter.
  7. Turn on the computer.

macbook-battery-cover-removed

MacBook Without A Removable Battery

  1. Shut down the computer.
  2. Plug in the power adapter.
  3. On the built-in keyboard, press the Shift, Control, and Option keys on the left side and the power button, all at the same time.
  4. Release all three keys at the same time.
  5. Turn on the computer.

Mac Pro, Intel-based iMac, Intel-based Mac mini, and Intel-based Xserve

  1. Shut down the computer.
  2. Unplug the power cord.
  3. Wait fifteen seconds.
  4. Plug in the power cord.
  5. Turn on the computer.

When you reset the SMC, you may see the indicator light on the MagSafe power adapter behave a big strangely at first; this is normal.

Resetting PRAM

  1. Shut down the computer.
  2. Press the power button.
  3. Before the grey screen appears, press the Command, Option, P, and R keys at the same time.
  4. Hold the keys until your computer restarts and you hear the startup sound a second time.
  5. Release the keys.

After you reset the PRAM, you might notice that some of your settings have been reset—things like the time, the volume, mouse settings and keyboard preferences MagicPrefs: Another Powerful Mouse & Trackpad App [Mac] MagicPrefs: Another Powerful Mouse & Trackpad App [Mac] Apple‘s upcoming OS Lion trackpad and mouse gestures don’t compare to what BetterTouchTool and another similar application, MagicPrefs, have to offer. These applications are for Mac users who find Apple‘s default click, tap, and two-finger... Read More , and other things like that. If you remember your previous computer settings, you should be able to get it back to normal in just a couple minutes.

Good to Know

While you shouldn’t have to reset the SMC or PRAM on a regular basis, it’s still good to know what they do and how to go about fixing issues that you may come across. If your computer’s behaving strangely and restarting the machine doesn’t help, you know what to do! You might also want to try one of these eight resources for troubleshooting your Mac 8 Troubleshooting Resources to Help You Fix Your Mac Problems 8 Troubleshooting Resources to Help You Fix Your Mac Problems Read More .

Have you ever had to reset the SMC and PRAM on your Mac?

Image credits: Young office worker staring at computer screen and adjusting glasses. (edited) via ShutterstockCarl Berkeley via flickr, akiraak2 via flickr, DeclanTM via flickr.

  1. Bruce Syvertsen
    August 25, 2016 at 11:10 am

    Hello,

    First time post, so my apologies if I have posted in the wrong area.
    But my Mid 2011 27" iMac is doing the spontaneous reboot thing as well. This only started after I did a clean El Capitan install.
    My video card has been replaced twice under Apple's warranty. After the 2nd replacement the computer was fine till the El Capitan install. The machine just reboots without warning. usually daily, once or maybe twice.

    I have reset the NVRAM and SMC.

    I have attached the kernel panic notice. I hope someone can help. This is a great computer but the problems driving me crazy.

    Thanks in advance.

    Anonymous UUID: 0DDD54D9-3010-8127-E460-6710F1E4D757

    Thu Aug 25 18:21:54 2016

    *** Panic Report ***
    panic(cpu 0 caller 0xffffff802cdce6fa): Kernel trap at 0xffffff7fad766a8e, type 14=page fault, registers:
    CR0: 0x000000008001003b, CR2: 0x000038250c8b4885, CR3: 0x00000000307c6000, CR4: 0x00000000000626e0
    RAX: 0x000038250c8b4865, RBX: 0xffffff805987a7c0, RCX: 0x0000000000000000, RDX: 0x0000000000000001
    RSP: 0xffffff92187f3830, RBP: 0xffffff92187f3880, RSI: 0x0000000000000050, RDI: 0xffffff802cdec600
    R8: 0xffffff804c630000, R9: 0x0000000000000000, R10: 0x0000000000190076, R11: 0x0000000000070000
    R12: 0xffffff802cdec600, R13: 0x0000432d62c533e1, R14: 0x0000000000190076, R15: 0x000000000000000a
    RFL: 0x0000000000010286, RIP: 0xffffff7fad766a8e, CS: 0x0000000000000008, SS: 0x0000000000000010
    Fault CR2: 0x000038250c8b4885, Error code: 0x0000000000000000, Fault CPU: 0x0, PL: 0

    Backtrace (CPU 0), Frame : Return Address
    0xffffff92187f34c0 : 0xffffff802ccdab52
    0xffffff92187f3540 : 0xffffff802cdce6fa
    0xffffff92187f3720 : 0xffffff802cdec563
    0xffffff92187f3740 : 0xffffff7fad766a8e
    0xffffff92187f3880 : 0xffffff7fad764134
    0xffffff92187f38e0 : 0xffffff7faffec3d1
    0xffffff92187f3950 : 0xffffff7fad76b66f
    0xffffff92187f39d0 : 0xffffff7fad76e1a1
    0xffffff92187f3a50 : 0xffffff7fad76d62c
    0xffffff92187f3aa0 : 0xffffff7fad76bd11
    0xffffff92187f3ae0 : 0xffffff7fad75b47f
    0xffffff92187f3b20 : 0xffffff7fad74bfa1
    0xffffff92187f3b70 : 0xffffff7fad751ff5
    0xffffff92187f3bb0 : 0xffffff7fad750d48
    0xffffff92187f3c20 : 0xffffff7fad74124c
    0xffffff92187f3cc0 : 0xffffff7fad73fc09
    0xffffff92187f3d00 : 0xffffff7fadda17d5
    0xffffff92187f3d80 : 0xffffff7fad5add90
    0xffffff92187f3e10 : 0xffffff802d2b6148
    0xffffff92187f3e80 : 0xffffff7fad5ad623
    0xffffff92187f3ee0 : 0xffffff7fad5b2935
    0xffffff92187f3f20 : 0xffffff7fad5b2693
    0xffffff92187f3f40 : 0xffffff802d2b2fb1
    0xffffff92187f3f80 : 0xffffff802d2b30a6
    0xffffff92187f3fb0 : 0xffffff802cdc9117
    Kernel Extensions in backtrace:
    com.apple.iokit.IOUSBHostFamily(1.0.1)[79D250A3-843A-3750-BE64-A252CF17A148]@0xffffff7fad578000->0xffffff7fad5e1fff
    dependency: com.apple.driver.AppleUSBHostMergeProperties(1.0.1)[401B7165-36E8-3EE5-849D-71DAEB3E46E4]@0xffffff7fad574000
    com.apple.iokit.IOHIDFamily(2.0)[9A3F90D7-1A6A-3FCD-9689-0BF6A66A29A2]@0xffffff7fad73b000->0xffffff7fad7b2fff
    dependency: com.apple.driver.AppleFDEKeyStore(28.30)[C31A19C9-8174-3E35-B2CD-3B1B237C0220]@0xffffff7fad730000
    com.apple.driver.usb.IOUSBHostHIDDevice(1.0.1)[AC74012B-CBBC-323B-B760-0E31B664B7B5]@0xffffff7fadd9c000->0xffffff7fadda5fff
    dependency: com.apple.iokit.IOHIDFamily(2.0.0)[9A3F90D7-1A6A-3FCD-9689-0BF6A66A29A2]@0xffffff7fad73b000
    dependency: com.apple.iokit.IOUSBHostFamily(1.0.1)[79D250A3-843A-3750-BE64-A252CF17A148]@0xffffff7fad578000
    com.spsys.driver.IOKitDriver(1.0.1)[00000000-0000-0000-0000-000000000000]@0xffffff7faffeb000->0xffffff7faffeefff
    dependency: com.apple.iokit.IOHIDFamily(2.0.0)[9A3F90D7-1A6A-3FCD-9689-0BF6A66A29A2]@0xffffff7fad73b000

    BSD process name corresponding to current thread: kernel_task

    Mac OS version:
    15G31

    Kernel version:
    Darwin Kernel Version 15.6.0: Thu Jun 23 18:25:34 PDT 2016; root:xnu-3248.60.10~1/RELEASE_X86_64
    Kernel UUID: B5AA8E3E-65B6-3D0E-867B-8DCCF81E536C
    Kernel slide: 0x000000002ca00000
    Kernel text base: 0xffffff802cc00000
    __HIB text base: 0xffffff802cb00000
    System model name: iMac12,2 (Mac-942B59F58194171B)

    System uptime in nanoseconds: 73862209830158
    last loaded kext at 33379638359613: com.Logitech.Contro

    Model: iMac12,2, BootROM IM121.0047.B23, 4 processors, Intel Core i7, 3.4 GHz, 16 GB, SMC 1.72f2
    Graphics: AMD Radeon HD 6970M, AMD Radeon HD 6970M, PCIe, 2048 MB
    Memory Module: BANK 0/DIMM0, 4 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353237334448302D4348392020
    Memory Module: BANK 1/DIMM0, 4 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353237334448302D4348392020
    Memory Module: BANK 0/DIMM1, 4 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353237334448302D4348392020
    Memory Module: BANK 1/DIMM1, 4 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353237334448302D4348392020
    AirPort: spairport_wireless_card_type_airport_extreme (0x168C, 0x9A), Atheros 9380: 4.0.74.0-P2P
    Bluetooth: Version 4.4.6f1 17910, 3 services, 27 devices, 1 incoming serial ports
    Network Service: Ethernet, Ethernet, en0
    Serial ATA Device: Hitachi HDS722020ALA330, 2 TB
    Serial ATA Device: APPLE SSD TS256C, 251 GB
    Serial ATA Device: HL-DT-STDVDRW GA32N
    USB Device: USB 2.0 Bus
    USB Device: Hub
    USB Device: Keyboard Hub
    USB Device: Apple Keyboard
    USB Device: IR Receiver
    USB Device: Card Reader
    USB Device: USB 2.0 Bus
    USB Device: FaceTime HD Camera (Built-in)
    USB Device: Hub
    USB Device: BRCM2046 Hub
    USB Device: Bluetooth USB Host Controller
    Thunderbolt Bus: iMac, Apple Inc., 22.1

    • Dann Albright
      August 31, 2016 at 6:44 pm

      I'm not technically adept enough to interpret the error message, but I'd say if you have continued problems, your best bet is to take it into a Genius Bar. They'll know what to do!

  2. Shahin
    August 21, 2016 at 9:22 am

    Hi Dann,

    My laptop kept switching off and I took it to the Apple store. After more than a week, they told me I need to change the logic board and the Battery as the SCM memory was full and need to change it. I am very familiar that the apple store 1st solution would be to replace half components. Would you rest work with my laptop? I do not feel the need to pay $800 more dollars to a laptop which i just bought 2 years ago. I think its daylight robbery. I would highly appreciate if you could mention an alternate way fix this if the above method doesn't work.

    Thanks and Regards
    Shahin

  3. Adam
    August 7, 2016 at 10:22 am

    Thanks so much, you saved me from eternal full power fan.

    • Adam
      August 7, 2016 at 10:23 am

      You also fixed my dodgy trackpad which I didn't even know would be fixed by this. Thanks sooooo much, I owe you one

    • Dann Albright
      August 16, 2016 at 2:02 pm

      No problem! Really glad that it helped. SMC/PRAM resets can fix a lot of things that you might not expect, which is why everyone should know about them!

  4. Angela
    August 4, 2016 at 1:31 pm

    Hello,
    I realize this post is a couple of years old.

    My 2011 MacBook Pro has been acting weird, and today while in light use my acreen turned white with horizontal gray lines so I shit off and it now appears to turn on with a gray horizontal line screen and the gray bar below the logo only fills halfway and doesn't turn on.

    I just follow your reset instructions for PRAM & SMC and nothing changes, no improvements.

    I'm in shock and scared the laptop is toast. Could you please guide me with what may be wrong with it and what is the safest next step?

    Thank you,
    G.

    • Andy
      August 22, 2016 at 3:28 pm

      Apple has a special program going til Dec 31st where they will replace your logic board for free since 2011 and 2012 macbook pros have a common problem with the GPU. Grey lines like that is the start of your GPU going bad. I'd take it in and have it fixed for free while you still can.

    • Dann Albright
      August 31, 2016 at 6:37 pm

      Thanks for the tip! I hadn't heard about that. That's definitely what you should do.

  5. Vinny
    April 14, 2016 at 12:27 pm

    My Mac Mini claims it has a max capacity of 8 GB but crucial.com claims it can accept 16 GB. Crucial advised me to do a NVRAM reset and that will allow Mac mini to accept 16GB of memory. Is this true?

    • Dann Albright
      April 18, 2016 at 1:44 pm

      Hm . . . I've never heard of it working that way, but it certainly seems possible. I'd give it a shot and see what happens.

  6. Destiny
    February 16, 2016 at 12:03 am

    Thanks for this post, Dann. Your description of signs that SMC isn't functioning fits what I'm experiencing *exactly*.

    • Dann Albright
      February 18, 2016 at 12:32 am

      I'm really glad you found it useful! It's an easy solution that more people should know about.

  7. Rafa Beccar Varela
    January 29, 2016 at 8:09 pm

    Hi all. After installing El Capitan on my MacBook Air mid 2011, iCloud, iTunes, App Store, FaceTime & iMessage, all of them fail to login or keeps loading forever. Could this options solve my issue? Thank you.

    • Dann Albright
      February 3, 2016 at 6:32 pm

      I'd say it's definitely worth a shot. Have you tried it?

    • Samantha
      June 3, 2016 at 11:54 am

      This happened to me after installing El Capitan, turns out my serial number was wiped from my computer and therefore I couldn't access those you mention. Also had trouble with switching my computer on etc. I had to visit the Genius Bar at the Apple store and while they managed to rewrite my serial number, they couldn't work out why my computer would take multiple attempts of holding down a number of keys in order to switch on and suggested it was time to get a new one! They did not mention an SMC reset and did not attempt this. I came across the SMC reset from googling and it seems to have sorted out my macbook air. Surely Apple should have told me about this, my macbook air showed all the signs of needing an SMC reset.

    • Dann Albright
      June 6, 2016 at 11:57 am

      I've never heard of that serial number issue; that's really weird! Did they say how that might have happened? Glad that the SMC reset seemed to help—is your computer still working alright? And yes, I'm surprised that the guys at the Genius Bar didn't discuss that with you. Seems pretty likely that they would have known about the warning signs and potential fix.

    • Samantha
      June 12, 2016 at 10:12 am

      Unfortunately after posting this I had issues again where it would shut down when the progress bar was at a certain point. I paid someone to try and fix it (he mentioned replacing the hard drive) but all he did was wipe everything, including my serial number again). It did work for a few days though and it still switches on alright but now where my wifi sign is it says wifi: no hardware installed. After looking online it seems the remedy for this is also smc reset which isn't working. Apple don't understand how my serial number was wiped, the guy said he'd never seen it before but I only knew to check mine because of others it had happened to after installing El Capitan, he said it could possibly be due to that. I think my MacBook has had it, if Apple can't help me I don't know how to find someone who can. Thanks

  8. Yasmindlr
    January 25, 2016 at 8:49 am

    Hello this happened to me before so i needed to restart my pram and it worked cntrl alt p r but it happenednagain and it doest work anymore... Makesthe sounds correctly but
    The screen says black.

    • Dann Albright
      January 28, 2016 at 7:22 pm

      Have you reset the SMC?

  9. Stephen
    January 3, 2016 at 7:07 am

    A few months ago I bought a USB hub, after plugging it in, my USB ports actted a little funny. Moving what was plugged in around and restarting seemed to fix it.
    But now when ever my computer goes into deep sleep or shits off, the fan kicks into high speed mode.
    I have done PRAM and SMC restarts with no fix.
    I had the same issue with my old iMac (2007) but back then you reset your SMC by holding down your power button for 15 secs. This new method for the new computers, I don't think it works 100% of the time. And as my computer is out of warrenty, plus a lack of funds taking it to a apple repair shop is out of the question, specially seeing as people who have had the same issue, said the apple techs said the whole motherboard would need to be replaced at like a cost of 700$

    I just want to know why a USB hub would even mess stuff up.

    • Dann Albright
      January 28, 2016 at 7:24 pm

      I've never heard of a USB hub doing anything like that. Have you found a solution to this issue yet? Sounds like something Apple might have to fix.

    • Stephen
      January 28, 2016 at 7:40 pm

      I am going to see if doing a clean instal will work; waiting to have internet reinstalled in my apartment.

      There are reports of this happening with USB hubs. I had the same issue years ago with a 2007 iMac, back then the SMC could be reset by the power button. Not any more.

    • Sam
      June 1, 2016 at 10:07 pm

      I've had just about the exact same issue.

      Have you found any solutions? Did either of these resets work?

    • kazumma
      June 6, 2016 at 12:16 am

      It's your hub. They will sometimes trigger your mouse...and will make the computer wake up. Unplug it and you will not have the issue anymore.

    • Dann Albright
      June 6, 2016 at 11:41 am

      Interesting! Is this an issue with all USB hubs, or just a certain make/model?

  10. Sandi Jull
    September 1, 2015 at 1:36 am

    Thank you! Never heard of the SMC (and I work at a help desk supporting Macs and PCs!). I've used PRAM many a time (especially in the days of the 7200s) but the SMC was the perfect fix for a student laptop today. She was suitably impressed!

    • Dann Albright
      September 2, 2015 at 9:42 pm

      Before I wrote this article, I wasn't aware of it either. Turns out it's extremely useful! Hopefully this article has helped get the word out—I'm sure there are a lot of people who could benefit from knowing what it is and how to reset it.

      Thanks for reading!

  11. katmarie33
    July 22, 2015 at 6:03 pm

    Hi, I reset my Macbook Pro's (2008, 15") SMC and PRAM, and now when I start up my computer, it won't let me log in to my user account. This error message pops up: "You are unable to log into the user account at this time..."

  12. Angie Miller
    July 14, 2015 at 9:14 pm

    I am having to reset the pram and the smc every single time I turn on my computer. I can't put it to sleep of I have the do the pram reset. occasionally after the smc reset i will get a loud fan and must shut it down and do another reset. Whey is this happening? What can I do?

    • Dann Albright
      July 25, 2015 at 2:52 pm

      You might want to bring your computer into an Apple store and have their techs look at it. That's not a problem I've come across before.

  13. Jason Burroughs
    June 30, 2015 at 4:29 pm

    Can you be more specific as to the steps for a machine like mine? I have a 2013 Macbook Pro retina.

    You say "On the built-in keyboard, press the Shift, Control, and Option keys on the left side and the power button, all at the same time." Then "Release all three keys at the same time." Then "Turn on the Computer"

    However, "release all three keys" doesn't make sense if you are holding down four keys!

    My issue is that I get a popup about icloud password every time i boot up. I recently switched to two step verification, and I think it's asking for an app specific password. As part of the troubleshooting, I'm trying to reset PRAM (done) and SMC.

    Let's take the steps like this, and please correct/add details:

    1. Power down the computer normally
    2. Ensure power cord is plugged in
    3. hold down the shift, control, and option keys all together
    4. press and release the power button
    5. note that there is no audible or visual cue that something has happened
    6. press and release the power button and computer turns on
    7. log in and use the computer as normal

    Does that sound like the physical steps you're using? If so, how can there be no confirmation that something is happening (like with PRAM, at least it dings over and over again if you hold down all the buttons). Maybe I'm just doing it wrong.

    • Dann Albright
      July 5, 2015 at 2:17 pm

      Yes, that should say "release all four keys at the same time." Once you've pressed and released shift, option, control, and power, your computer shouldn't turn on. That's why "turn on the computer" is the next step. So you're correct in thinking that there's no confirmation—I'm not sure why that's the case, but I've never had any sort of confirmation on my machine.

      I don't know if resetting the PRAM and SMC will solve your iCloud password problem. What happens when you enter your iCloud password?

    • Curtis Loeb
      September 10, 2015 at 1:23 pm

      If you look closely you will notice on the MagSafe power cord where the magnet plugs into the side of the computer the tiny LED light will change from Amber color to green and back to Amber that is the confirmation that the SMC was reset

    • Dann Albright
      September 11, 2015 at 10:09 pm

      Ah, I wasn't aware of that! Thanks for pointing that out—definitely a good thing to know.

    • Matete
      December 24, 2015 at 9:17 am

      ... is this available also for a macbookpro from 2009? ...

    • Dann Albright
      January 2, 2016 at 1:35 am

      The MagSafe light indicator, you mean? I would imagine that it is. Have you tried resetting the SMC on your computer?

  14. Lana Wetherald
    May 25, 2015 at 6:59 pm

    I literally cannot thank you enough. You saved me so much time and money and Apple-related stress, this was the only thing that worked!

    • Dann Albright
      June 12, 2015 at 1:46 pm

      I'm really glad to hear that it was helpful! This is a common fix that a lot more people should know about.

      Thanks for reading!

  15. Anonymous
    May 22, 2015 at 3:09 pm

    hi i tried to do a smc reset too good luck there my shift buttons doesn't work I'm waiting for parts to change all keyboard i just had problems with both macbook pro very disappointed after spending so much money

    • Dann Albright
      May 23, 2015 at 8:56 am

      That's a problem . . . if your buttons aren't working, you might need more than just an SMC reset.

  16. Andy
    May 18, 2015 at 6:04 am

    Everywhere I've read the SMC advice, it says to remove the plug "for 15 seconds". I assume it means "at least" 15 seconds - or is the time critical?

    If I turn my computer off every night at the wall, does this achieve the same thing?

    • Dann Albright
      May 19, 2015 at 6:44 am

      As far as I know, it's at least 15 seconds, and it doesn't have to be exact. As for turning your computer off at the wall . . . I'm not sure. If you want to reset the SMC, though, I'd use the procedure above. You shouldn't need to reset it every night.

  17. Marilia
    May 4, 2015 at 1:34 pm

    My "P" button (and other buttons as ?;:0_-) are not working. How should I press to reset PRAM?

    • Dann Albright
      May 19, 2015 at 6:43 am

      That's a tough one . . . I'd head to an Apple store. I'm not sure if there's much you can do about that!

    • Gregory Fleming
      June 7, 2015 at 9:13 pm

      external usb keyboard?

  18. Jeff
    March 22, 2015 at 8:54 pm

    Hi, read through all of these posts and wondering if anyone can assist?
    I have a 15" Macbook Pro with Retina display that is just over a year old and it will not turn on. I've tried SMC reset (Shift-Control-Option) but it doesn't do anything, nor does a PRAM reset.
    LED indicator on "T" style MagSafe adapter is green but MacBook does not respond........any ideas?

    • Dann Albright
      March 29, 2015 at 7:20 pm

      I'd bring that to the Apple store; if neither of these resets are helping, you might need some more serious work done. Let us know how it turns out!

    • Kish Kontent
      June 15, 2015 at 7:20 pm

      Hi Jeff, did you manage to fix your mac?
      I have the same Macbook with the same problem and mine is only a year old as well this month. Please share any new information you might have. Thank you.

  19. James Ford
    March 20, 2015 at 8:56 pm

    Hello, I have an 2010 MacBook pro that is randomly shutting down on me anytime that I try to run some hefty programs, and even sometime if I run more then one program. Sometime just starting her up make it shut down. I have trying to restart the SMC, but I am not sure if I did it correctly or that was just not the solution.
    I am not sure what to do and I need to get some work done SOON. Any suggestions?

    • Dann Albright
      March 29, 2015 at 7:20 pm

      Have you tried resetting the PRAM as well? Also, 2010 means the computer's four or five years old, so you might be having some age-related problems; that's about how long mine last when I use them all the time.

  20. Frank
    March 12, 2015 at 2:28 am

    I did the shift safe mode restart thing and it stayed loading for about 25 minutes, now I just tried restarting the pram but this is also taking a while to change, how long does it take until it boots up ? I started having problems while plugging a USB in the computer and then it froze. Now I just have a grey screen with the apple logo and a loading dotted circle moving

    • Dann Albright
      March 12, 2015 at 7:37 am

      It certainly shouldn't take 25 minutes to boot. Try resetting both PRAM and SMC and see if that helps at all. Hopefully that'll get you back up and running!

  21. Declan
    March 12, 2015 at 2:14 am

    Hi,I have an 06 macbook, for a while the battery has been unrecognised and it shows the x symbol where it should be a thunderbolt... Iv reset the smc with an initial change but then defaults back to the x symbol.. This evening I replaced the connection from the logic board to the battery and still no further forward after the resets... I checked with a Mac repair shop and their is no fault with the battery... I'm at a loss really, any ideas?
    Thanks in advance, Dec.

    • Dann Albright
      March 12, 2015 at 7:41 am

      Hm . . . that's a tough one. Though I have to say that you've been able to keep a Macbook running for 9 years! That's pretty impressive.

      After doing a little research, I haven't come up with a whole lot on this. Some people have seen the X symbol when they have a bad battery, but if the shop says that the battery's alright, and you also replaced the connection from the logic board, I'm not sure what else you can do. Call Apple, maybe? They might be able to help out.

      Sorry I don't have any better advice—that's a tough one!

  22. Fred
    March 10, 2015 at 5:39 pm

    Hi All & Nick

    I have to say I have exactly the same problem...... meaning, when I boot, I have the apple logo, the progress bar. when the bar is filled, then the computer shuts down and nothing happens. If I start again, same process... I have tried the PRAM reset ? (CMD ALT P R) but same bar again....

    Nick: where do you stand ?

    Many thanks

  23. Carl
    March 6, 2015 at 1:57 am

    Macbook Air keyboard became completely unresponsive. Was able to shut it down but now it won't turn on. I tried the SMC reset but it still won't turn on. Power indicator turns green for about a second after the reset so it seems to be getting the message but it still won't power on.

    Unit is just a bit over a year old and out of warranty - go figure!!

    Any thoughts?

    • Dann Albright
      March 8, 2015 at 4:39 pm

      Have you tried a PRAM reset? If that doesn't work, I'd take it into an Apple store. That doesn't sound good.

    • Katy
      May 2, 2015 at 10:53 pm

      Did you have any luck fixing your issue. It sounds like I am having the same problem.

  24. Nick
    March 2, 2015 at 10:28 pm

    After a weekend of trying things I finally managed to login on the acct I use most. It was running slow, then shutdown on its own. Similar problems happened, couldnt boot to anything but single user mode, Target disk, or option boot. Finally made it in after running the two commands suggested in safe mode. I logged in using a less used account and it ran normally. Ran Disk Utility to verify permissions, repair permissions, and verify HD. Permission found a bunch of things from the printer driver I recently installed. I'm afraid to shutdown. What should I do to troubleshoot the slow user acct while logged in normally?

    • Dann Albright
      March 3, 2015 at 8:57 am

      Man, I'm sorry to hear that—that sounds pretty rough. At this point, your best bet might be to take it to a Genius Bar. Sounds like you could have a pretty big problem somewhere in there. Sorry I don't have any better advice. Let us know what you find out—this could be helpful to other people if you get it figured out!

  25. Nick
    February 28, 2015 at 3:40 pm

    After doing a PRAM reset that left the computer shutdown, I tried an SMC reset. My computer is now in a continuous cycle. The der-di sound happens, the apple and status bar appears. After status bar fills in, blank grey screen, then the computer restarts.

    It has been doing this for about 15 minutes. I think it is not working correctly. What is supposed to happen?

    • Dann Albright
      March 2, 2015 at 5:51 pm

      Have you found a solution? That's not one that I've heard of. If the battery runs down and then the computer starts up again, that could potentially kick it out of the loop.

  26. Nick
    February 28, 2015 at 3:06 pm

    I did the PRAM reset. It restarted and chimed again and I released all of the keys. Then the apple logo and progress bar appeared. Then a grey screen with nothing on it. And then it shutdown again. Is this normal?

  27. C
    February 12, 2015 at 11:36 pm

    I got a Bluetooth speaker. When connected to my Macbook Pro it was cutting out and sometimes lagging. Soooo annoying! But it worked fine with my iPhone, so I thought it couldn't be something wrong with the speaker itself. I thought there was nothing I could do until I got a new computer!

    The SMC thing did the trick. THANK YOU!!

    • Dann Albright
      February 13, 2015 at 7:19 am

      The list of problems that a PRAM / SMC restart can solve just keeps growing! That's a really good one to know.

      Thanks for sharing that tip!

  28. Alan Ellicott
    February 6, 2015 at 3:07 pm

    Just had a further recollection of the first incident above. If your internal fan refuses to switch itself off, this may be an SMC issue as that was a further symptom that was cured.

    • Alan Ellicott
      February 10, 2015 at 10:54 am

      Dann,
      All I know is that whatever the SMC reset corrected was preventing the OS's to boot.
      I would imagine that if the SMC is relevant to whether or not a hardware component is present and identified, it may mean that until it has sorted its act out, the loading of drivers in whatever OS would be affected. Certainly the Windows 7 startup was freezing on the inability to load a video driver. When I ran SMC reset, it went straight through.
      First time round, MAC OS was unaffected (except that any reference to batteries or power information was missing from the System details), however second time this too failed to boot until SMC recycled.
      I have no doubts about what happened to my trusty old white macbook (2009) - still keeps going and has had a rebirth having installed an SSD drive 6 months ago.

    • Dann Albright
      February 10, 2015 at 2:09 pm

      A white Macbook with an SSD? That's pretty awesome. I upgraded to the Macbook Air when my white Macbook died, but I really loved it while I had it. Very cool idea.

  29. Alan Ellicott
    February 6, 2015 at 2:17 pm

    Many thanks for SMC instructions.
    Just posting this as it may help others.

    It is becoming obvious to me that the SMC reboot can cure an assortment of problems so I am listing my two in case they help someone.

    What appears to happen is that something goes wrong with the hardware controller thingy which (apart from causing lights not to come on ) can often prevent the OS loading. This can be Mac OS or Windows.

    First time:
    About 3 monts ago my white macbook failed to boot in Windows (stumbling on a driver issue) but was OK as a Mac however at the same time the magnetic charger green light was not showing as charged/charging and the system description inside the MacOs showed no battery.

    An SMC reboot solved the issues and it has been working fine since then.

    Todays issue:
    This morning would boot in Windows safe mode but stumbled half way thru booting as a Mac. Would not boot as normal Bootstrap Windows 7) No charger light issues but not talking to my monitor sharing device. Again an SMC reboot solved the problem and i can breathe a sigh of relief. The ONLY thing I did before it went wrong was to go into Display settings in Windows and change what was the main screen. How that could affevrt the SMC, I don't know!

    So, when all else fails, remove power supply, take the battery out, hold down the power button for 5 secs and put battery back in, plug in power supply and restart.

    Not widely publicised enough. I wonder how many people have thrown their MACs away unnecessarilly?

    • Dann Albright
      February 10, 2015 at 10:18 am

      Thanks for sharing your experience! I don't have a lot of experience with dual-booting, but I wonder how using Windows could affect the SMC. If just doing a reset will solve the problem, it's not a big deal, but still an interesting issue.

      Glad to know that the SMC reboot helped! I'm learning more and more all the time about the sorts of issues that it can help—sounds like a lot of people would have benefitted from it. Hopefully not too many replaced their computers because of those problems. :-)

  30. Shamanrawb
    February 5, 2015 at 8:01 pm

    I've got a weird one. I did a Artic silver job on my heat sink in my MacBook pro and lowered my
    Temps while gaming to around 80c. It was mid 90s. Ok. That was a few weeks ago. I was having some ram leak issues, so today I did a pram and smc reset. Now while gaming my temps are in the mid 90s to 103c again. And I'm in a colder room

    Thoughts?

    • Dann Albright
      February 6, 2015 at 9:08 am

      That IS a weird one. The only thing I can think of is that it's possible that some settings changes that you made to manage your heat issues could have been reset when you did the SMC/PRAM reset. If you can think of any changes you made that way, that would be a good place to start. Did you change any fan speed settings?

      Other than that, I have no idea. That's very strange. If anyone else has had this problem, hopefully they can share what they did to fix it!

  31. Dan
    February 1, 2015 at 8:22 pm

    By the way, Dann - thanks for this article, and for all of the comments.

  32. Dan
    February 1, 2015 at 8:13 pm

    For about a month, I've been experiencing a number of the problems listed here, including the fan running at high speed, computer shutting down by itself, slow performance, and kernel crashes - on my Intel based Mac Pro tower. Today I replaced the 3V battery on the mother board. Since the problems have been intermittent, it's too soon to say whether I'm out of the woods completely. But I will say without a doubt that the machine is noticeably faster and more responsive now.

    • Dann Albright
      February 2, 2015 at 6:53 am

      Ah, that's an interesting solution to the problem. I can see why a faulty battery on the motherboard would cause problems. While that's beyond my technical expertise, it's great to know that it's a potential solution to these types of problems.

      Thanks for sharing that strategy!

      (And to address your subsequent comment, you're very welcome—I'm really glad to hear that you found it useful!)

  33. JackieO
    February 1, 2015 at 6:34 am

    My Mac book pro (Retina 15 inch late 2013 2.3 GHz i7 512 SSD) was taking a while to start up. Would power on and would stay in the black screen for about 30 to 45 seconds before starting up.
    Took a systematic approach and used disk utility to verify and repair disk permissions. Had some issues with printer directories.
    Restarted. Still had a issue.
    Verify Disk with Disk Utility. No issues found.
    Reset SMC. Tested restart still took time.
    Reset PRAM. Tested restart and it fixed the issue.

    Not sure if all the steps made a difference but it now starts up quickly again.

    Thanks for the information

    • Dann Albright
      February 1, 2015 at 7:32 am

      Glad to hear that the PRAM reset was helpful! Even if the other steps weren't crucial for solving that particular problem, it's still a good idea to go through them methodically, because you never know what could cause an issue next.

      Thanks for sharing your experience!

  34. Jay Grissom
    January 26, 2015 at 11:36 pm

    Hi Dann,

    Thanks so much for this! I'm still not really sure why this worked... but your article is some good insight.

    For the last few days my 2009 iMac (3.06 GHZ PROC, 8GB RAM, Crucial 500GB SSD) has just started to beach ball.

    Click on a task in Things app get a "beach ball" (wait for 30 seconds).
    Click on a paragraph in a Pages document get a "beach ball" (wait for 30 seconds).
    Click on a link in Safari get a "beach ball" (wait for 30 seconds).

    It got OLD REALLY fast.

    But your hint on the weirdness of the Mac's behavior was a clue to try this... Thanks! The system has been up for a bit and it's like I have a new iMac again.

    I can't imagine how this stuff get's gunked up but thanks for sharing the gunk cleanup plan here...

    Much much much appreciated!

    Sincerely,
    Jay

    • Dann Albright
      January 27, 2015 at 10:49 am

      Really glad that you found the article helpful! Your problem sounds really frustrating, and I'm sure it's a huge relief to have found a way to fix it.

      Thanks for reading!

  35. Marta
    January 22, 2015 at 5:39 pm

    I have a Macbook Air and the problems consistent with problems in the SMC. Tried resetting but did not work.. What should I do next?

    • Dann Albright
      January 24, 2015 at 9:34 am

      Have you also tried resetting the PRAM? That would be my first suggestion. Beyond that, I'd say head to a Genius Bar. :-)

  36. Shep
    January 18, 2015 at 9:37 am

    My 2013 Macbook Pro 13" does not sleep when the lid is shut, just the screen, hard drive and fans still running. Nothing is running in background. Any thoughts?

    • Dann Albright
      January 19, 2015 at 6:02 pm

      Have you tried resetting the PRAM and SMC? That might help, though it sounds like you might have some sort of hardware issue—it's possible that the sensor that tells the computer it's closed is broken. Might want to have that checked out. Let us know what you find out!

    • Chris
      April 12, 2015 at 8:21 pm

      I am having the same issue. Any fixes?

  37. jf
    December 31, 2014 at 9:06 pm

    I have to use these about every 6 months on my old PowerMac G5 because the firewire ports stop working ("unable to list firewire devices"). Always works fine after!

    • Dann Albright
      January 1, 2015 at 1:11 pm

      That's a great way to use these resets. I'm always impressed at how many different sorts of problems they solve. Thanks for reading!

  38. Cindy
    December 29, 2014 at 11:34 pm

    Have a mini mac that we changed the resolution on and now the computer is locked and asks for us to change the computer screen resolution. How do I fix the issue?

    • Dann Albright
      December 31, 2014 at 2:56 pm

      Hm . . . not sure about that. Have you tried both of the resets detailed above? If you have, and that doesn't help, I'd recommend asking your question in the Answers section of the site. There are a lot of very technical people there that can help!

  39. thatmanphil
    December 14, 2014 at 9:08 am

    My macbook pro will only start after an SMC restart. anyone have similar problem?

    • Dann Albright
      December 20, 2014 at 10:53 am

      Strange . . . I've definitely never heard of that. How old is your Pro? Hopefully someone else can chime in with some advice!

    • gosia
      February 11, 2015 at 6:45 pm

      I have exactly this some problem with my macbook pro from mid 2010..

    • neil
      May 24, 2015 at 5:20 am

      i have a 2014 mac air ,first time to mac and will be last time i have had so much trouble, now my mac boots up but you can't do anything for about 15 min, i have tried lots of things

  40. Neal
    December 12, 2014 at 3:13 pm

    I started having mouse issues last year (jerky performance, jumping around, etc.). Did the PRAM thing a few times and while it didn't eliminate the problem, it helped significantly and made the mac usable again. After finally installing Mavericks in October, the problem returned, but until the other day it wasn't nearly as bad as before. Since the other day it's suddenly gotten much worse and I'm going to flush the PRAM again after writing this comment.

    • Dann Albright
      December 20, 2014 at 10:52 am

      Did that help? And have you reset the SMC? That might improve things a bit, too.

    • Anonymous
      February 27, 2015 at 8:53 am

      Doug, I love my macs but they have problems sometimes.

  41. Doug
    November 26, 2014 at 3:13 pm

    Yeah, this whole article is false. Macs just work... What, are you new?

    • Zeni
      May 16, 2015 at 12:33 pm

      Macs are basically built using roughly the same [cheap] components used for building PCs, which is the main reason components fail every now and then. You sound like a Windoz PC guy, which makes me believe you've never actually used a Mac long enough to realize that it is the SYSTEM that makes the difference, not the specs. (or at all). The main issue that slows down any OS is the age of the hard drive, and Macs are certainly not spared. SSDs nowadays almost eliminate this issue. On Mac the system itself rarely gives any errors, and "it just works" means that you can literally launch ALL the applications you have installed, at the same time, and they will all start (with a very slight delay as they clutter toward the end of the list). Good luck trying that on a Windoz PC, no matter how new, expensive and performant it is. So while we, dumb Mac people relax doing fun stuff on our Mac, you smart people have fun waiting for Windoz to just start….doing….something…. :))))

  42. Doc
    November 26, 2014 at 12:47 am

    But...but..."it just works!" LOL.

    • Dann Albright
      November 26, 2014 at 3:46 pm

      Haha—well, in most cases, that may be true. But every once in a while, "it just works" needs a bit of a push in the right direction. :-)

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