I'm sorry to hear that your iMac is experiencing issues with unexpected reboots. Random reboots can be caused by various factors, including software or hardware problems. Let's try some troubleshooting steps to see if we can resolve the issue.
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Check for software updates: Make sure your macOS is up to date by going to the Apple menu () in the top-left corner of the screen, selecting "System Preferences," and then clicking on "Software Update." Install any available updates.
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Check for incompatible software: If you recently installed any new software or made changes to your system, it's possible that it could be causing conflicts leading to the reboots. Try uninstalling any recently installed software or disabling any new system extensions to see if that resolves the issue.
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Safe mode: Booting your iMac in Safe Mode can help identify if the issue is caused by third-party software. Restart your iMac and immediately press and hold the Shift key until the Apple logo appears. If your iMac doesn't reboot randomly while in Safe Mode, it suggests that the problem is related to software or drivers.
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Hardware diagnostics: Your iMac has built-in hardware diagnostics that can help identify if there are any hardware problems. Restart your iMac and immediately press and hold the D key until the Apple Hardware Test or Apple Diagnostics screen appears. Follow the on-screen instructions to run the diagnostics and check if any hardware issues are detected.
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Reset SMC and NVRAM: Resetting the System Management Controller (SMC) and Non-Volatile Random Access Memory (NVRAM) can sometimes resolve unexpected issues. Here's how to do it:
- Reset SMC: Shut down your iMac, then press and hold the power button for about 10 seconds. Release the button, wait a few seconds, and then turn on your iMac.
- Reset NVRAM: Restart your iMac and immediately press and hold the Option, Command, P, and R keys simultaneously. Keep holding the keys until your iMac restarts and you hear the startup sound for the second time.
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Check for overheating: Overheating can cause your iMac to shut down unexpectedly. Ensure that the vents on the back of your iMac are clear and not obstructed. You can also use third-party software to monitor the temperature of your iMac's components.
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If the issue persists after trying these steps, it may be necessary to contact Apple Support or take your iMac to an authorized service provider for further assistance. They can provide more specialized help based on your specific situation
Hope this helps,
CXDeaks