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#Mac restart hold d diagnostics mac
It spends a few minutes checking the Mac and repairing things if necessary and it can fix certain problems. Hold down D while starting the Mac to start the Apple Diagnostics utility - let go when you see a screen asking for your language. Just wait a couple of minutes and restart as normal. You don't have to do anything in safe mode. Caches are cleared and the disk is checked. It is a minimal startup and extensions, non-standard fonts and other things are not loaded. Start the Mac in safe mode by tapping the power key to turn it on and then hold down Shift. The timing is probably important, so have your watch, an Apple Watch of course, next to you when you do this. Five seconds later, press the power button to turn on the Mac. Wait 15 seconds and plug the power cable back in. Shut down the Mac and unplug the power cable. The iMac and Mac mini are different again. Select Controller in the Hardware section and you will see, or not see, the T2 chip. Not sure if your MacBook has a T2 chip? Click the Apple menu, hold down Option and click System Information. Switch on with the power button in the usual way. Hold them for 10 seconds, then release all of the buttons. Press the Shift+Ctrl+Option buttons on the left side of the keyboard and the power button all at the same time. On older MacBooks with no T2 chip made before 2018, shut down the computer. Release them all and tap the power button to turn on the Mac. Keep holding the keys down for another 7 seconds.
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Then press the power button, if your Mac is on, it will turn off. On the left side of the keyboard, press Ctrl+Option+Shift for 7 seconds, the Mac might turn on. It does not reset it, but this procedure can fix some problems. Let go, then press the power button to start the MacBook as normal. On a MacBook with a T2 security chip, which was introduced in 2018, shut down the MacBook and then press and hold the power button for 10 seconds. You just might need to configure a lot of settings afterwards. It is not the first thing to try because it has such wide-ranging effects on the system. Resetting the SMC should be done as a last resort when you have tried everything else and have failed to solve the problem you are having. It controls the CPU, which affects the system performance, the bounce of Dock icons, video mode switching and more. It controls the power, including the power button, battery charging, sleep mode, opening and closing the lid. The SMC controls all the lights, like the keyboard backlight, the status indicator, battery indicator, and display backlight. If the fan is blowing all the time then resetting the SMC can help.
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This performs a lot of functions and among them is the system fan, if your Mac has one. The NVRAM/PRAM is not the only component that stores system settings and there is another called the SMC, short for System Management Controller. Relase the keys after the second startup sound (old Macs) or after the second Apple logo appears (new Macs). Let go of those keys and the Mac will then boot up as it normally does, but with default NVRAM/PRAM settings.Īfter resetting the NVRAM/PRAM, you might need to open System Settings and select the startup disk, screen resolution, time, and sound if the defaults are not to your liking. Press the power button and straight away press and hold down the Command+Option+P+R keys. To do this, turn up the volume to the maximum, then power off your Mac. It remembers the screen resolution so it can restart with the same settings, and more.Īny problems you are having with these components, and a few more, could be caused by corrupt NVRAM or PRAM and may be fixed by clearing it and started with a clean slate. It stores the name/location of the startup disk in case you have two or more drives, or partitions with Bootcamp and so on. NVRAM or PRAM is used to store information like the speaker volume so that it is set at the same level next time you power on. A new one is required - get expert help because it is on the motherboard.Įven if the battery is OK, for some unknown reason the contents of this memory can become corrupted or it might contain wrong settings and this can affect the running of the computer. If an iMac keeps forgetting things like the sound volume or time zone, it may be becuse the battery is dead. MacBooks have a big battery of course, but desktop iMacs have little one too, so they can maintain the NVRAM contents. Basically, it is memory that retains its contents even when the power is switched off. On old Macs it is called PRAM, which stands for Parameter RAM, but on recent Macs it is called NVRAM (Non-Volatile RAM). The Apple Mac has a small amount of special memory that it uses to store a variety of important system settings. If you have tried everything else and problems persist, try these tricks. Hold down these keys when the Mac starts up to fix a variety of strange problems with Apple iMacs and MacBooks.