• Random Access Memory is a temporary storage medium that your Mac’s CPU uses for fast access to data it’s processing. The CPU can access data contained in RAM much faster than it can data held.
• Rember is actually a GUI for the popular command line memory testing tool called.

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

Reply

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.)

Reply

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?

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

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Rember is an amazing app! In regards to the comment above:

it closes all windows because to free-up whole RAM memory for tests.
It’s understandable that you must save your work before you open any diagnostic app.

Works great on latest 2019 iMac where Memtest failed and Apple Diagnostic Tool is a JOKE

Reply

Rember

I ran this app and it closed all open windows and running apps without asking or warning me. That is bad software. Who knows what data I lost as a result, let alone time in reopening what I can remember was running. memtest does not do this.

Reply

Ram Test For Mac

Hope this works well, thanks!

Reply

Tip

Hey,

Stress testing your Mac is a useful way to work out if it is performing to its best and to determine if there are any faults within the various components. Stress testing your Mac is also a useful way to determine if you Mac has a fault if it is using 100% of a CPU, or if there is bad memory. Today’s post is going to describe three ways to stress test the core components of your Mac, CPU, RAM and disk. By testing each one to the ‘max’ you can determine if there is a problem and if you Mac can handle the heat.

Stress Testing The CPU

Stress testing your CPU is probably the simplest of the three core components of your Mac. To test your CPU to the max, open Terminal located in your Applications > Utilities folder.

We are going to use the ‘yes’ command to test the CPU. This command prints out the letter ‘y’ as fast as possible. The result of this means it uses 100% of a CPU core. To use this command type the following and hit enter.

yes > /dev/null

This executes this yes command. It then pipes this data to /dev/null/ . This means we don’t see any output. If you want to see the output of a million ‘y’ characters on screen remove the ‘> /dev/null’ reference.

You will notice in your activity monitor that one CPU will shoot up to 100%. Putting load onto your system. If you have more than one core, open a new terminal window and type the command again. Repeat for as many cores that you have on your Mac. Not that due to the use of hyper-threading you may need to use more than the number of physical cores on your Mac to fully load the system . To find out how many physical cores your Mac has got to the hardware report section of System Information / About this mac.

Using the ‘yes’ command can load a CPU. Add more commands to use up every resource.

To stop the test use Control + C to kill the command. Alternatively you can close the Terminal window. This will load your system and is a good representation of a fully loaded system.

Stress Testing Your RAM

RAM is a little bit harder to test. Instead of pure speed we need to look to see if there is any problems with the chips. To stress test your RAM we are going to use memtest (direct link to the package here). Install the package and open up Terminal.

Ram Stress Test For Mac

With Terminal open type the following to test your RAM.

memtest all 1

This will test every byte of RAM your Mac has access to once. If you want to continue testing your RAM indefinitely use the following command:

memtest all

If you want to test a small portion of your RAM you can use the command:

memtest 100 1

This will test 100mb of RAM once.

The test will loop through your Mac testing it for a variety of problems.

You will notice that memtest will only test a small subset of free memory available to you. You could close every program on your Mac, but this still won’t test every byte of RAM. To test it all you will have to boot into single user mode. Restart your Mac and as it reboots hold Command + S. Once it has finished booting you will see a black screen with white text. Type memtest all 2 to test every bit of available RAM. Restart to get back to norma.

Stress Testing Your Hard Disk Drive

The final core component of your Mac is the hard disk drive. The crucial component that holds all of your data. Over time these degrade and slow down. To stress test your hard disk drive for speed and performance we can use a tool called Blackmagic Disk Speed Test free from the app store. When you load the app select the disk drive you want to test. Then select the size of file you want to write. I recommend the largest of 5GB.

Hit the start button and it will test the read and write performance your your disk drive. It will keep doing this until you tell it to stop. Note, if you get an error saying it cannot write to the disk, select your user folder or something similar. Sometimes selecting the root of a drive causes an unwritable error message.

Ram Memory Test For Mac

Write and read as fast as possible to test your disk speed.

You can save the result of the disk speed for later use. My SSD drive has only slowed by a couple of tenths of a megabyte over the last year. Its a good way to see if your Mac can handle the disk speed read/write load.

Bench Marking App

Check My Ram Memory Online

All of these separate tests are useful, as well as free. However, if you want some more concrete numbers and a more repeatable test I recommend you download and buy Geekbench from the App Store.

This app tests your CPU and RAM in a more controlled way. At the end it gives you a score which you can save and compare later. I recommend you close down every app since the final score can be heavily influenced by what apps are running.

Conclusion

There are many ways to stress test your Mac. Most of the methods are free and give you good results. It is always interesting to see how your Mac shapes up over time.

Stress testing can also be a good insight into any possible failures. Especially with testing using memtest, if there is a fault on your RAM chips, it will find it.

Ram Test Software For Mac

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