Imac turns on then off

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Question:Q:Imac starts up then shuts down

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Question:Q:

Hi There - I have an imac that was running mavericks, and I always ran time machine daily. Last week I went to start up my machine and it stayed in the grey start up screen and an empty status bar appeared, and then it just simply turned off. And that is where it stands today. Does this mean my machine is dead, or is there still possiblity of life?

iMac, OS X Mavericks (10.9.1)

Posted on Sep 8, 2016 9:03 AM

Sep 8, 2016 9:23 AM in response to Mark Haket In response to Mark Haket

Don't give up! There may be hope yet.

Did your iMac startup to the light gray screen with a dark gray Apple Logo or does it still remain at a blank gray screen?

Regardless, disconnect all peripherals (directly connected to the iMac) except the keyboard and mouse. Can you get to the User logon or home screen now?

If not, a number of possibilities can be the issue.

The next thing to try is to boot up your iMac in Safe Mode. To do so, power-on or restart your iMac and immediately hold down the Shift key when you hear the boot chime. Continue to hold it down until, hopefully, your iMac boots up to the logon screen.

Safe Mode will bypass all but the most essential system software, so if the problem is with a third-party system extension, then this will suggest that you need to tackle your software and add-ons to fix the problem. If Save Mode does NOT allow your system to boot, then the problem is deeper in the OS configuration and further troubleshooting will be required.

Sep 8, 2016 9:23 AM

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Sep 8, 2016 9:23 AM in response to Mark Haket In response to Mark Haket

Don't give up! There may be hope yet.

Did your iMac startup to the light gray screen with a dark gray Apple Logo or does it still remain at a blank gray screen?

Regardless, disconnect all peripherals (directly connected to the iMac) except the keyboard and mouse. Can you get to the User logon or home screen now?

If not, a number of possibilities can be the issue.

The next thing to try is to boot up your iMac in Safe Mode. To do so, power-on or restart your iMac and immediately hold down the Shift key when you hear the boot chime. Continue to hold it down until, hopefully, your iMac boots up to the logon screen.

Safe Mode will bypass all but the most essential system software, so if the problem is with a third-party system extension, then this will suggest that you need to tackle your software and add-ons to fix the problem. If Save Mode does NOT allow your system to boot, then the problem is deeper in the OS configuration and further troubleshooting will be required.

Sep 8, 2016 9:23 AM

Sep 8, 2016 9:54 AM in response to Tesserax In response to Tesserax

Hi Tesseax - It did start up with a light gray screen with a dar gray apple logo. I did disconnect everything except the keyboard and mouse, and I cannot get to the user login. I did try to reboot in safe mode and nothing happened. Does it matter that it is a wireless keyboard, or should i get a wired keyboard to do it?

Sep 8, 2016 9:54 AM

Sep 8, 2016 10:12 AM in response to Mark Haket In response to Mark Haket

Ok, got it. Thanks for clarifying that for me.

Yes, it may be possible that you are not able to get into Safe Mode because you are using a wireless keyboard. If you do have a wired one handy, it will definitely help.

Since your iMac did make it to the Apple Logo screen, the following could be the reasons why it won't go any farther:

  • A required service failed to load
  • Stalled network services
  • Selections in the Directory Access application
  • The Mac is set to search for a particular server at startup and the server is not available
  • Corrupt files and permissions errors in the /System/Library
  • Corrupt or missing plist files in /System/Library/Preferences
  • Missing or corrupt EFI partition.

Please try getting into Safe Mode using a wired keyboard.

Sep 8, 2016 10:12 AM

Sep 8, 2016 1:02 PM in response to Tesserax In response to Tesserax

Ok, tried it with a wired keyboard while holding down the shift key, and still the same results. It simply just shuts down:(

Sep 8, 2016 1:02 PM

Sep 8, 2016 2:29 PM in response to Mark Haket In response to Mark Haket

I had this issue (would chime, screen goes grey, status bar would go about halfway then it would turn itself off, and continue to do this over and over until i pressed the power off button on the back) and after a month or so of trying to fix it, I took it into the Genius bar and it turned out to be the graphics card was dead. 388GBP to put it right, it now turns on, but I can't connect to wifi. (not sure if this is linked in anyway?!)

Sep 8, 2016 2:29 PM

Sep 8, 2016 2:40 PM in response to Agnieszka G In response to Agnieszka G

Not sure I understand. What happened when you pressed the power button on the back? Did you do this while the screen was gray?

Sep 8, 2016 2:40 PM

Sep 8, 2016 2:50 PM in response to Mark Haket In response to Mark Haket

I pressed the power button on the back to turn it off otherwise it would be in a continual loop of starting up, grey screen with progress bar, shutting down then starting up....over and over. Only way to stop it was to turn it off from the back. I went through some checks with an online chat apple person that made me hold down different buttons at different times, but nothing would work. The guy in the Apple genius bar said nothing I could do would have made it work as the graphics card was broken

Sep 8, 2016 2:50 PM

Sep 8, 2016 2:54 PM in response to Agnieszka G In response to Agnieszka G

Ok, thank you for clearing that up for me. I'm afraid I might have to take it in as well. Hope you can get your wifi issue taken care of.

Sep 8, 2016 2:54 PM

User profile for user: Mark Haket Mark Haket

Question:Q:Imac starts up then shuts down

Sours: https://discussions.apple.com/thread/7658756

How to Fix a Mac that Randomly Shuts Off

Authored by:
Support.com Tech Pro Team
This Guided Path® was written and reviewed by Support.com’s Tech Pro team. With decades of experience, our Tech Pros are passionate about making technology work for you. We love feedback! Let us know what you think about this Guided Path® by rating it at the end.

Introduction

Sometimes you may experience your Mac to abruptly shut off while performing your daily tasks. This can be frustrating especially if it's happening repeatedly.

This guide will take you through some troubleshooting steps that may help fix this issue. The steps are listed in order, so start with the first one, see if that helps, and then continue with the next one if it doesn't.

iMac

1 Check the Mac's Power Connection

Make sure the Mac is powered up properly by checking the electrical connections.

  1. Make sure you are using a working electrical outlet. You can test another electric device, such as a lamp, with the same outlet. Bypass any power strips for troubleshooting purposes.
    Lamp outline.
  2. Make sure the power connections to and from the Mac are proper. Choose the type of Mac you have below.

2 Check the Computer's Ventilation

Computers heat up while they're running and their internal parts need to be cooled down and kept at a certain temperature to perform optimally. If the computer overheats it may result in it shutting down to prevent damage to its components. In worst cases, the components may also melt or get fried if the computer is kept running at a high temperature. To check whether your computer still has working fans, try the following:

  1. Look for any vents your computer may have: in the back, on the side or bottom.
    Vents pointed out on read of desktop PC.
    Vents pointed out on side of laptop.
  2. With the computer turned on, place your hand in front of the vents and feel if there is any air blowing.

    The longer the computer is turned on and the more complex the tasks it needs to perform, the warmer and stronger the air flow should be.

  3. Depending on your results, you will have three options:
    • There is no air blowing – This could mean the fans are not working and the computer has no cooling.

      Please contact the product manufacturer for further assistance.

    • The air flow feels weak – The computer's fans may have dirt built up on and inside them which is causing them to slow down and not blow enough air to properly cool down the internal components. This can be fixed by cleaning up the outside and inside of the computer, and oiling up the fans.
    • The air flow feels normal – This could mean the issue the computer is having is software related. There are a few different software fixes that may be attempted to resolve the issue.

3 Clean the Computer's Vents

If you had a computer for more then a few months, it is likely to have accumulated some dirt inside and out. Dust, grime, hair and other debris can build up on fans, heatsinks and other parts. Components can also come loose or become unseated over time. All these can affect a computers performance in a negative way.
Dust buildup inside a computer.

This is a generic method on how to clean the vents for any type of computer. If your computer looks differently than the one represented in the picture below, the steps you need to follow are exactly the same.

Using a compressed air duster is the best and most recommended way of cleaning a computers vents.

When blowing compressed air, keep the can upright at all times and never shake it to prevent the liquid refrigerant from leaking onto your electronics. Use short bursts of two or three seconds. When the can gets too cold to hold, set it down for a few minutes until it warms up again.

  1. Turn the computer off and unplug its power cable.
  2. Locate the air vents or other openings.
  3. Blow compressed air to clean up the vents or other openings.
    Using gas duster to clean laptop vents.
  4. Once done, reconnect the power cable and turn the computer on to test it out.

If the Computer Is Still Overheating

Please contact the product manufacturer for further assistance.

4 Check for Updates

  1. Select the Apple menu, then App Store.
    macOS Mojave Apple Menu with App Store highlighted.
  2. You will now see the app store pull up. Select Updates.

Any version of macOS 10.7 (Lion) or older can check for available updates through the Apple Menu and Software Updates.

5 Reinstall macOS

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If your Mac starts up to an Apple logo or progress bar

Your Mac shows an Apple logo when it finds your local startup disk, then shows a progress bar as the macOS startup or installation process continues.

Apple logo with progress bar

Your Mac shows an Apple logo when it finds your startup disk, which is usually the disk built into your Mac. As startup continues, you should see a progress bar, with or without the Apple logo. This screen might alternate with a blank screen several times.

If you're installing macOS, the Apple logo or progress bar might persist for much longer than usual. As installation continues, the progress bar might move slowly and pause for long periods. That's why Apple recommends beginning macOS installation in the evening—so that it can complete overnight, if needed.

If your Mac is stuck on this screen

If you think you've waited long enough to know that your Mac is stuck on this screen, follow these steps.

  1. Press and hold the power button on your Mac for up to 10 seconds, until your Mac turns off. Then turn your Mac back on.
  2. If the issue persists, press and hold the power button until your Mac turns off. Then unplug all accessories from your Mac, including printers, drives, USB hubs, and other nonessential devices. You could have an issue with one or more of those devices or their cables. Then turn your Mac back on.
  3. If the issue persists, once again press and hold the power button until your Mac turns off. Then use Disk Utility to repair your startup disk.
    • If Disk Utility found no errors, reinstall macOS.
    • If Disk Utility found errors and repaired them, restart your Mac. If the issue returns after restarting, reinstall macOS.
  4. If you still need help, please contact Apple Support.

Published Date: 

Sours: https://support.apple.com/en-us/HT207019
Mac shuts down in few seconds at startup- FIXED!!

Why does my iMac shutdown halfway through loading on startup?

I get a chime then the Apple logo appears, then the progress bar gets to about halfway, then it shuts down.

Specs

  • Late 2009 27" iMac Intel Core Duo 3.06ghz
  • 128GB Samsung SSD installed in place of Optical Drive.
  • Stock 1TB HD
  • 12GB RAM, 2x4GB and 2x2GB. The 2x2GB sticks are the stock RAM.
  • OSX Yosemite.

Background Info

  • I haven't used the iMac in about a month as I have a Macbook Pro from work that I use primarily.
  • I turned on the iMac yesterday and the Startup was VERY SLOW, like 5 minutes.
  • I looked at some forums and saw that I should make my SSD my primary boot drive. I did this and restarted but the boot time was the same.
  • Next I shutdown the computer and restarted the SMC. This made the boot time a little bit faster, maybe 2 minutes but it still wasn't acceptable.
  • Next I reset the NVRAM 3x and this made a significant improvement. It was now at about 25 seconds.
  • When I finally logged in I opened up Photoshop and Firefox and they both just bounced on the task bar for about 2 minutes. Photoshop finally opened but Mozilla did not. I looked in the Activity Monitor and I kept getting CrashReports that were taking up 75% of the system.
  • I did some googling and it seemed like I needed to run First Aid on the SSD.
  • I went to Disk Utility and tried Verifying the Disk and it gave me an error saying that it could not be verified and that I would need to open it up in Recovery Mode.
  • I restarted the computer and held down CMD+R and nothing happened, it just stayed on the white screen. I held down the power button until it shutdown and the powered it back up holding option. It showed that I did not have a recovery partition (even though I remember having one in the past). It did show my Samsung Drive.
  • I clicked on the Samsung Partition and it loaded about halfway then shutdown.
  • I tried just starting the computer up normally without holding anything down and it would do the same thing.
  • I decided that I didn't have anything on the computer that I desperately needed so I was just going to reinstall Yosemite.
  • I downloaded Yosemite on my MBP and made a bootable USB drive for it. (This took about 4 hours).
  • I went back to my iMac and plugged the USB drive in, turned on the iMac, and held down option (expecting that it would give me the option to boot from the USB Yosemite Installer) and it chimed, the apple logo came on, the loading bar got to halfway, and it shutdown.
  • I tried this about 5 times and it did the same thing.
  • I tried resetting the NVRAM and it just shuts down.
  • I've tried Safe Mode, resetting the SMC, option, etc. Nothing works.
  • I left it unplugged over night and tried starting up this morning and I get the same thing.
  • Yesterday I took out the 2x4GB ram sticks and made sure the stock 2x2GB sticks were properly seated. I tried resetting the NVRAM and it still loads halfway and then shuts down.

I don't know what else to try. When I used it more often a couple of months ago it was very fast upon start up and running memory intensive programs like Reason, Autodesk Inventor, Parallels, Ableton Live, etc.

I am very comfortable taking the computer apart I just don't know what to look for.

Thanks for the help,

Kyle

Sours: https://www.ifixit.com/Answers/View/218110/Why+does+my+iMac+shutdown+halfway+through+loading+on+startup

Turns on off imac then

iMac Shuts Down Randomly: How to Fix It

Did your iMac suddenly shut down while doing your regular tasks for the day? Once or twice and it must have been just a glitch. However, if this has happened on multiple occasions, it might be time to inspect your iMac for any underlying problems. There are some troubleshooting steps that you can take to check what might be causing your iMac to shut down randomly. Here are some things you can do to fix this issue.

iMac Shuts Down Randomly? Do This:

Check the Power Connection of Your iMac

Is your iMac powered up properly? Check all the electrical connections in your iMac as well as the electrical outlet. It’s possible that your iMac is working just fine but your electrical outlet isn’t. To check, try connecting another electric device to the same electrical outlet. If it doesn’t turn on, then you know that the electrical outlet is the problem. However, if it does, the next step is to check your iMac and its connections.

Obviously, your iMac gets power from the power socket. Check the cables that you’re using to plug your iMac into an electrical outlet. The cables and connectors you’re using might have some visible damages that you haven’t noticed before. If they do, you’ll have to replace them and check if your iMac faces the same issue again. Also, make sure that both ends of the cables are firmly plugged. If they are loose, they might be causing the issue of your iMac randomly shutting down.

Inspect Your iMac’s Ventilation

As with all engines, they heat up over time while running. The same also applies to devices like your iMac. Fans and vents are installed to help cool down the internal parts of your iMac. Through this, your device would be able to perform at its optimal condition. However, if they overheat, it’s possible for your iMac to shut down to prevent damaging its internal parts for good.

Consequently, you should check if your iMac’s ventilation is still clear and working properly. This is how to inspect it the right way:

  1. Spot the vents of your iMac. They’re located along the bottom edge of the screen. There are also vents located on the back of your iMac.
  2. While your iMac is still on, place your hand across the vents. Do you feel any air blowing out of the vents? Here are some scenarios:
  3. You can’t feel any air blowing out of the vents. This means that the fans inside your iMac may not be working properly. Hence, it’s overheating, which might be causing your iMac to shut down randomly. Bring your iMac to a Genius Bar and have it checked and fixed.
  4. You can feel some air blowing out of the vents but it seems pretty weak. If that’s the case, then the problem probably lies in the state of the fans. It’s working but there might be some built-up dirt or debris that’s causing it to slow down. At this rate, your iMac is not getting cooled down as fast as it should. Consider having your iMac cleaned inside and out.
  5. You can feel air blowing out of the vents and it feels normal. If it’s not a hardware issue, you’ll have to consider that there might an underlying software problem. Now, there are different software fixes depending on the actual software problem. So you’ll have to investigate all the apps in your iMac.

Update or Reinstall macOS

Should it be a software issue, you can first check all the apps you’re using in your iMac. Are there any apps that you recently installed prior to your iMac acting up? Try removing these apps from your device and check if it solves the issue. If it doesn’t, try checking for macOS updates. It might just be a bug that the latest macOS can fix. However, if your iMac still randomly shuts down, you can try reinstalling macOS.

Before reinstallation, make sure to back up all your data. This is because the reinstallation of macOS will erase all programs and files on your iMac. After you’ve had your data backed up, this is how to reinstall macOS on your iMac:

  1. Located on the upper left corner of your screen, click on the Apple Menu and select Restart.
  2. Right after your iMac reboots, press and hold Command + R. Release the keys when you see the Apple logo appear on your screen.
  3. Choose Reinstall macOS. A window will prompt you to select Continue.
  4. The setup of macOS will start. Click on Continue.
  5. A window will ask you to accept the Terms of Service. Select Agree.
  6. A follow-up confirmation of the acceptance of the Terms of Service will appear. Select Agree.
  7. Select the drive you wish to install macOS in. After this, click on Install.
  8. Installation of macOS will begin after this and may take some time. Your iMac will also restart during the installation process. After installation, you can now log into your iMac again. Check to see if the reinstallation fixed the problem.

If these fixes still won’t work, it might be high time to seek the help of a professional. Set up an appointment with a Genius Bar and have your iMac checked by the experts. They should be able to help you find what’s causing the issue and solve your problem. There might be a deeper issue in your iMac that only a professional can fix.


Featured Photo by bongkarn thanyakij from Pexels

Filed Under: MacTagged With: iMac, troubleshooting

Sours: https://www.applegazette.com/mac/imac-shuts-down-randomly-how-to-fix-it/
Fix: Macbook pro shuts down itself at startup while booting

Late 2010 iMac getting quarter way in booting then turning off

Late 2010 iMac getting quarter way through booting then turning off


Ok - first things first, apologies for a long post - I have lots of details about this issue.


Context:


As far as I can remember, about a couple of weeks ago I was working on my iMac (Late 2010, I believe running High Sierra) and it got stuck and froze (the spinning rainbow wheel of doom).

I waited for about 5 minutes then force shut down the iMac using the button. From there, the iMac simply refused to start up. It would get halfway through a very slow boot up - i.e. loading bar gets halfway - then simply turn off and die.

Here is what I have tried, and the various results for each:


My attempts:


  1. Safe Mode - I attempted to boot into Safe Mode by holding when I turned the computer on. Unfortunately it simply doesn't get to Safe Mode, the iMac turns off half way.

  2. Recovery Mode - I attempted to boot into Recovery Mode by holding + and succeeded, but when I attempted to perform first-aid on the drive, I got this:

Recovery Mode Results

  1. Booting into a different drive - I only have the recovery drive separate, so same result as (2).

  2. Performed Apple Diagnostics (on my iMac known as Apple Hardware Test) by holding on startup. I ended up with error code -3403D.

  3. Reset NVRAM multiple times by pressing + + + - no change.

  4. Reset SMC multiple times by unplugging. No change.

  5. Booted into Verbose Mode - everything went smoothly until it got to checking the , where it stopped, before spewing an error message and shutting down after 3 seconds.

  6. Booted into Single Boot Mode by holding + on startup and typing . I repeated this over and over but it didn't say anything different, just that the drive couldn't be verified completely.


Question:


I'm aware there may be ways to fix this by reinstalling MacOS. I'm also aware that this could be a hard drive issue, however, I'd like to exhaust all other options before I consider that. Are there any other ways anybody knows hot to fix this?


Note:


I'd like to note that now, a few weeks after the initial issue the iMac only makes it quarter way through the boot before turning off.

I'd also like to note that I have seen these websites:

https://www.stellarinfo.com/blog/solved-macbook-pro-booting-stuck-halfway/

https://discussions.apple.com/thread/8464773

https://discussions.apple.com/thread/8381789

https://discussions.apple.com/thread/7051661

https://www.ifixit.com/Answers/View/218110/Why+does+my+iMac+shutdown+halfway+through+loading+on+startup

iMac gets stuck halfway through boot

But nothing has worked. Can the Apple Stack Exchange Community help me better?


Thanks!


Sours: https://apple.stackexchange.com/questions/412438/late-2010-imac-getting-quarter-way-in-booting-then-turning-off

Similar news:

Mac Won't Boot or Start? How to Fix Issues With a Mac Not Turning On

Got an iMac or MacBook Air that won't turn on, or maybe won't boot past the Apple logo? Don't worry. It's frustrating, but usually fixable.

Here are all the steps you need to get your Mac started again. Just work through them in order, unless your Mac won't boot after a failed operating system update. In that case, skip straight to step 8.

Where Is the Power Button on a MacBook?

Before you get started, make sure you know how to turn on your Mac.

On newer MacBook models, the power button is the unmarked black square on the top-right of the keyboard. This also doubles as the Touch ID sensor; you just need to briefly press your finger on it to power on your computer.

On an older MacBook, the power button is a clearly marked physical button. It's in the same location on the top-right of the keyboard, alongside the function keys.

You can find the circular power button on an iMac around the rear, bottom-left corner (when looking at your computer from the front). On a Mac Mini, the power button is on the rear, right corner.

1. Check If the Mac Has Power

First, check that your Mac has a power source. Yes, it's silly and obvious, but anyone who's done tech support knows that you have to get the obvious fixes out of the way first.

So if your MacBook won't boot on battery power, plug it in. The battery may be fully depleted, or could be malfunctioning.

If your MacBook won't charge or turn on with the power adapter connected, make sure it's connected properly and not damaged in any way. Try a different power cable, if you've got one around. Also, check that the port is clean. A buildup of dust can disrupt both USB-C ports and older MagSafe chargers.

And while you're at it, check your external hardware as well. Disconnect any peripherals like printers or graphics tablets, as these can sometimes be the cause. If you've got a Mac Mini, make sure the monitor is connected and powered properly.

2. Run a Power Cycle

The next step is to run a power cycle. This completely cuts all traces of power from the Mac and enables you to restart it from scratch.

  • On a recent MacBook, including the Apple silicon models, disconnect the power cable and hold the power button down for 10 seconds.
  • For an older MacBook, disconnect the power cable and remove the battery for at least 10 seconds.
  • If you're using a desktop Mac, disconnect the power cord for at least 10 seconds.

Now reconnect the power and try to restart your Mac. This move may be enough to spring it to life.

Holding the power button down like this is the equivalent to pressing a "reset" button or pulling the plug. It works on phones, ebook readers, and pretty much every other gadget that doesn't allow you to remove the battery, so it's a good tip to remember.

3. Boot in Safe Mode

When your MacBook won't boot, try to remember what you were doing the last time it was working. Were you installing apps, fiddling with fonts, or tweaking the system?

If your Mac shows signs of life when you power it on—if it won't go past the Apple logo or login screen, for example—then booting into Safe Mode may help you fix it.

On an M1 Mac, turn it off, then press and hold the power button until you see the Startup Options load. Now select your main drive, press the Shift key, and select Continue in Safe Mode.

On older Macs, press the power button and immediately press and hold the Shift key. Keep it held until you reach the login screen, then continue as normal.

Safe mode runs a bunch diagnostic tests, then boots a stripped-down version of macOS. This doesn't load your startup apps, custom fonts, extra hardware features, or anything else beyond the basics.

If your Mac boots successfully into Safe mode, you can start uninstalling any new apps, disabling startup items, removing hardware, or undoing any other recent changes that may cause the problem.

4. Reset SMC

The System Management Controller (SMC) controls a host of basic Mac functions. It handles everything from the keyboard backlight, to battery management, to what happens when you press the power button.

Resetting the SMC is a good catch-all solution to many problems, including if your MacBook won't start or it won't wake up when you open the lid. There are a few ways to do it, depending on what model of Mac you've got.

You don't need to reset the SMC at all if you've got a Mac that uses Apple silicon.

Desktop Intel Macs

  1. Unplug the power cord and wait 15 seconds.
  2. Plug the cord back in and wait another five seconds.
  3. Restart your Mac.

2018 MacBook Pro + MacBooks With T2 Security Chip

  1. Press and hold the right Shift key, the left Option key (Alt), and the left Control key for seven seconds.
  2. While keeping these keys pressed, hold down the power button for another seven seconds.
  3. Release all the keys, wait a few seconds, then restart.

Intel MacBooks Without Removable Batteries

  1. Press and hold the left Shift, Option (Alt), and Control keys, plus the power button (or Touch ID button) for 10 seconds.
  2. Release all the keys, then restart your computer.

Older MacBooks With a Removable Battery

  1. Remove the battery.
  2. Press and hold the power button for five seconds.
  3. Reconnect the battery, then restart the MacBook.

5. Reset NVRAM or PRAM

NVRAM (non-volatile random access memory) is a special section of memory that stores certain settings a Mac needs to access quickly. Although problems with this are less likely to render your computer unbootable, resetting it as a precaution will do no harm.

Again, you don't need to do this on a Mac with Apple silicon.

Older Macs used PRAM (perimeter RAM) instead. The process for resetting either is the same:

  1. Press the power button, then immediately press and hold the Option (Alt), Command, P, and R keys.
  2. Keep the keys pressed for around 20 seconds, even if your Mac appears to restart.
  3. If your Mac plays a startup sound, release the keys after you hear it chime for the second time.
  4. If your Mac has the T2 Chip, release the keys after the Apple logo disappears for the second time.

When your Mac has restarted, you'll find that some basic settings like time zone or volume level might need adjusting.

6. Run Apple Diagnostics

Hopefully by now, your Mac is up and running again. If not, you can check for hardware issues by using the Apple Diagnostics tool. This will check for problems, then either suggest fixes or show your support options.

  1. Disconnect any unnecessary external devices, such as a printer. You can leave your keyboard, mouse, and monitor plugged in if needed.
  2. Press the power button.
  3. Press and hold the D key. Keep it pressed until you see a screen asking you to select your language.
  4. Pick a language, then Apple Diagnostics will begin running its tests. These take a few minutes to complete.

When done, you'll see the results of the test. Some will suggest quick fixes, then give you the chance to re-run the test. Others will generate reference codes which you can look up on the Apple Diagnostics page. It'll also show your Mac support options. If there are no issues, then the fault likely is not with your hardware.

On Macs released before June 2013, you'll get the Apple Hardware Test instead. You activate it in the same way, and the principle is the same. Select your language, then click Test to begin.

7. Use Recovery Mode Tools

All Macs have a special Recovery partition on the hard drive. This boots independently of the full macOS and gives you access to a suite of tools for repairing your computer.

To boot into Recovery:

  1. Press the power button.
  2. Press and hold the Command and R keys.
  3. Release the keys when you see the Apple logo.
  4. When it finishes booting, you'll see a new macOS Utilities menu.

The one to try first is Disk Utility. This is a version of the same tool that's available in macOS and enables you to scan and repair your hard drive or SSD. Select the drive and click First Aid to begin the repair process.

There are a few more tools available through the Utilities menu. These include the Terminal for more advanced users.

8. Reinstall macOS in Recovery Mode

If you've gotten this far, then it's likely that your problem is not hardware-related, nor is it a simple software fix. The best solution now is to restore a Time Machine backup, or reinstall macOS entirely.

You can do this through Recovery. Get started by pressing the power button and holding down the Command and R keys.

If you've got a recent Time Machine backup, you can restore that to see if it solves your problem. If not, choose Reinstall macOS from the menu.

When you choose to reinstall macOS, you're given the option to format your disk as part of the process. Don't select this if you simply want to repair your installation—there's no problem with reinstalling macOS on top of itself.

Follow the onscreen guide to complete the installation. You'll need to be connected to the internet, as the tool will download the operating system from scratch. If you can't get to this, you might need to boot your Mac from a USB drive.

Check for Other Warning Signs on Your Mac

All Macs, whether a high-end MacBook Pro or an older iMac, have great reputations for reliability. But they can still run into problems.

Although it's often relatively easy to fix a Mac that's not turning on, it's best to check for warning signs and patch up problems before they strike.

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About The Author
Andy Betts (218 Articles Published)

Andy is a former print journalist and magazine editor who has been writing about technology for 15 years. In that time he has contributed to countless publications and produced copywriting work for large tech companies. He has also provided expert comment for the media and hosted panels at industry events.

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