MemTest for Mac OS X Tests your RAM
If you have recently upgraded your Mac RAM or are experiencing strange system crashes, it’s a good idea to test your memory modules integrity using a free tool called memtest.
Download MemTest for Mac for Free
Memtest is from the broader UNIX world and it that has been ported to Mac OS X. For whatever reason, there are some websites who are charging for the free utility, but you should not need to pay for it:
- Download MemTest now (direct download link)
The above link downloads a zipped package installer that simply places the memtest port in /usr/bin and does nothing else.
Test your Macs RAM
Once you have installed memtest for Mac, launch the Terminal and type the following command:
memtest all 2
Memtest will take a little while (15+ minutes is not unusual) and you’ll see an actively updated screen like the screenshot above showing progress of the app. The command will test your RAM twice, which is generally enough to detect errors, but for unusual system freezes and crashes it can be a good idea to test your memory longer by removing the ’2′:
memtest all
Without specifying a number of passes at the end, the app run a long time but can be stopped any time by hitting Control+C in the terminal window. Letting memtest run a while will consume a lot of CPU cycles so if you’re going to run the utility on a Mac laptop be sure to plug it in first.
Error Reports and Bad RAM
If any errors are reported, memtest will let you know. Likewise, if you run memtest and the utility freezes or crashes, that’s a pretty good indicator that your RAM is bad. If you’re running the test and you encounter any errors or freezes, you should return the memory modules to the place of purchase and get a replacement.
I’ve used this utility for a while now and never run into any problems with Mac RAM, but it does happen from time to time. If you have recently bought an upgrade it’s always a good idea to use this app to verify that what you bought is trouble-free.
You can read a bit more about this memtest for Mac port at Command-Tab.com.
memtest is a windows utility too, always use it
Please make a comment here on how to remove it again
Control+C quits memtest
or to remove it:
cd /usr/bin/
sudo rm memtest
There’s not much reason to delete it though, it’s about 160k
nice tool, work nice
Thanks.
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Good article, thanks, and helped me solve my Macbook crashes OSX 10.6.8. However, I downloaded Memtest from SourceForge AppleJack project. Nice thing is the Readme file gave more info, a better user interface for dummies like me AND you get the other Applejack utilities – all for free.
They are already working on a Lion version.
http://sourceforge.net/projects/applejack/
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Hi,
I have 8GB ram but memtestosx shows “Memory Page Size: 4096″. Any suggestion? Thanks,
I’m testing a 16GB machine and also have the same “memory page size”. This is just the size of the memory chunks that get paged in and out, in bytes.
A couple of lines down you should see “Requested memory:”/”Available memory:”/”Allocated memory:”. This is the amount of memory not in use already that is going to get tested. Mine is 12934MB.
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Thanks! My memory passed, but it only took 22 seconds, not 15min…so I wonder if I did something wrong…
Feb ’11 Macbook Pro, 500gig, 8gb, Lion
Thank you for this. My memory from Newegg runs really well. =]
If I recive a tok as result in Bit Flip during a memtest, what it’s mind
How reliable is memtest? I just upgrade to 16GB for my 2011 Oct Mac Mini and memtest failed 1 out of 3 loops due to “FAILURE! Data mismatch at local BUFA address”. I’m wondering if I should RMA the 16GB memory sticks?
Thanks
Try to reboot with the Apple Hardware Test to confirm as well, but if you continue to get memory errors you should probably get them swapped out. Sometimes memory works, but you will run into random crashes and problems with the computer, personally if my memory and hardware tests kept failing, I would swap them out.
I bought and installed 16GB upgrade to my MB Pro. The memtest has so far passed 9 out of 10 times. The only one error I received (at the second iteration) was in the Checkerboard, failure at 60, all other times it’s gone through flawlessly. Not sure if I should be concerned.
Correct me if I’m wrong, but isn’t the maximum memory capacity of MBP 8 gigs?
Perhaps thats why you fell into the problem
The “official” word from Apple is that the MBP line only accepts 8GB. However, according to numerous sources – and confirmed installations – it can actually handle up to 16GB. If it’s any indication, both Crucial and Macsales (OWC) confirm this when you use their system specific memory selectors.