Diagnostic Utilities For Mac

To use any of these key combinations, press and hold the keys immediately after pressing the power button to turn on your Mac, or after your Mac begins to restart. Keep holding until the described behavior occurs.

If you’re having problems with a disk, Disk Utility can check the disk and repair problems it detects. How to repair a disk To browse the Disk Utility User Guide, click Table of Contents at the top of the page. Download and install the best free apps for Diagnostic Software on Windows, Mac, iOS, and Android from CNET Download.com, your trusted source for the top software picks. On your Mac, choose Apple menu Restart, then press and hold the D key while your Mac restarts. Keep holding the D key until the screen listing different languages appears. Select a language. Apple Diagnostics starts automatically. When Apple Diagnostics is finished, it lists any problems it finds. (The reference code is for use by Apple Support.). Once set up, our diagnostic drive will contain the following: A full installer for OS X Mountain Lion. A standard installation of OS X Mountain Lion. Some simple but useful utilities to resurrect a troublesome Mac. Let’s quickly go over each of these services that our drive will do. Data Lifeguard Diagnostic for Windows. GoodSync for WD. Install WD Discovery for Windows. WD Drive Utilities for Windows. WD Security for Windows. Western Digital Dashboard. Software for Mac GoodSync for WD. Install WD Discovery for Mac. WD Drive Utilities for Mac.

Command (⌘)-R: Start up from the built-in macOS Recovery system. Or use Option-Command-R or Shift-Option-Command-R to start up from macOS Recovery over the Internet. macOS Recovery installs different versions of macOS, depending on the key combination you use while starting up. If your Mac is using a firmware password, you're prompted to enter the password.
Option (⌥) or Alt: Start up to Startup Manager, which allows you to choose other available startup disks or volumes. If your Mac is using a firmware password, you're prompted to enter the password.
Option-Command-P-R:Reset NVRAM or PRAM. If your Mac is using a firmware password, it ignores this key combination or starts up from macOS Recovery.
Shift (⇧): Start up in safe mode. Disabled when using a firmware password.
D: Start up to the Apple Diagnostics utility. Or use Option-Dto start up to this utility over the Internet. Disabled when using a firmware password.
N: Start up from a NetBoot server, if your Mac supports network startup volumes. To use the default boot image on the server, hold down Option-N instead. Disabled when using a firmware password.
Command-S: Start up in single-user mode. Disabled in macOS Mojave or later, or when using a firmware password.
T: Start up in target disk mode. Disabled when using a firmware password.
Command-V: Start up in verbose mode. Disabled when using a firmware password.
Eject (⏏) or F12 or mouse button or trackpad button: Eject removable media, such as an optical disc. Disabled when using a firmware password.

If a key combination doesn't work

If a key combination doesn't work at startup, one of these these solutions might help:

Be sure to press and hold all keys in the combination together, not one at a time.
Shut down your Mac. Then press the power button to turn on your Mac. Then press and hold the keys as your Mac starts up.
Wait a few seconds before pressing the keys, to give your Mac more time to recognize the keyboard as it starts up. Some keyboards have a light that flashes briefly at startup, indicating that the keyboard is recognized and ready for use.
If you're using a wireless keyboard, plug it into your Mac, if possible. Or use your built-in keyboard or a wired keyboard. If you're using a keyboard made for a PC, such as a keyboard with a Windows logo, try a keyboard made for Mac.
If you're using Boot Camp to start up from Microsoft Windows, set Startup Disk preferences to start up from macOS instead. Then shut down or restart and try again.

Remember that some key combinations are disabled when your Mac is using a firmware password.

Learn more

Learn what to do if your Mac doesn't turn on.
Learn about Mac keyboard shortcuts that you can use after your Mac has started up.

Mac can be conveniently purchased from the Apple store and most of configuration allows you to upgrade the memory so that you don’t need to open the case and take the risk in using an incompatible memory which would cause system lockups.

The only thing is the upgrade from Apple store cost a lot more money if compared to the one that it purchased from a computer store. For example, an additional 2GB of memory cost $50 at Apple Store while it only cost less than $10 if you search in Pricewatch. If you’re willing to take the risk in adding extra memory in your Mac either to save money or perhaps you have a few lying around, it is best to run a memory test to make sure that the RAM is fully compatible and won’t make your Mac unstable.

Here we suggest 3 different methods to easily run a memory test on your Mac OS X including the latest Mountain Lion 10.8.

1. Rember

Rember is actually a GUI for the popular command line memory testing tool called Memtest OS X. Instead of typing commands in terminal, you can run the test by clicking a button. You are able to test a selected amount or all of the memory, specify the number of times the tests should run and also viewing of the log. Rember includes Memtest OS X in the package so there is no need to manually download and install the memtest. Running Rember will show a table displaying the detected memory on your Mac. Select the amount of memory to test, number of loops and click the Test button to start checking the memory. When the tests is finished, Rember will show the test results.

Rember runs in Mac OS X which means that not all of the ram can be tested due to a portion of RAM being reserved for housekeeping.

Download Rember

2. Memtest86+

If your Mac has a SuperDrive, you can burn the pre-compiled bootable ISO image of the Memtest86+ and boot up the Mac with the disc. Just press and hold the C key when starting up Mac to boot from the disc.

The good thing about Memtest86+ is it runs by itself without relying on the operating system, giving you a more accurate memory test result.

Download Memtest86+

3. Apple Hardware Test

This is the recommended way by Apple to test your memory using their diagnostic tool. If you have an installation disc, insert the disc, restart your Mac, press and hold the C key. Select the language for the Apple Hardware Test and click the Test button to start testing. You can also tick the “Perform extended testing” option which would perform a more thorough test that takes considerably more time to complete. On the latest Mac OS X Mountain Lion, the Apple Hardware Test is already pre-installed and it doesn’t come with an installation disc. Simply boot up, press and hold the D key to start the Apple Hardware Test.

You can also see the amount of memory installed on your Mac at the Hardware Profile tab to confirm that the memory is correctly installed and detected. There are some Apple Hardware Test images that can be downloaded for older models. Do note that the Apple Hardware Test images are machine specific meaning that you cannot use the iBook version on a Mac Mini.

Download Apple Hardware Test

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Night3 months ago

‘Closing all apps’ is an option which can be set or disabled in the Rember preferences.

I’m trying to test DRAM one bank at a time in mid-2010 Mac mini with 2 banks of 4GB Kingston DRAM each.

Rember run overnight on max cycles (255) showed when both banks were full (8GB total), there was a DRAM failure. But run overnight on max cycles (255), Rember is so slow it’s completed less than 30 cycles. I tried this twice.

Is it not possible to check one 4GB stick at a time? (Mid-2010 Mac mini standard RAM is 1GB module in each bank for total 2GB.)

Charlzm10 months ago

I have several DDR3 DIMMs I want to install, but the memory timing is not printed on them. Is there an app for Macs that can tell you what the timing is on installed DIMMs?

Diagnostic Software For Mac

Rember doesn’t shut down existing programs… you do that yerself

Rakiki1 year ago