MemTest for Mac OS X Tests your RAM
If you have recently upgraded your Mac RAM, or if you are experiencing strange system crashes, it’s a good idea to test your memory modules integrity using a free tool called memtest.
Essentially, memtest is a utility designed to stress test RAM for errors. Without getting overly technical in the explanation, memtest works by writing random data to the RAM, then verifying that the data written to the RAM is readable and without conflict. If errors are detected using this method, it typically means there is a faulty memory module, and that’s why memtest is such a valuable tool. Though it’s technical in nature, it’s quite easy to use, so let’s begin.
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 because it is free, open source, and there are Mac versions available from developers as free downloads:
- 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
This will immediately launch memtest, testing all modules twice (thus why the 2 is attached to the command). You can specify another number of tests to perform by replacing that, but two is fairly standard if you aren’t experiencing anything unusual.
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. Again, the aforementioned 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′, and then letting memtest run repeatedly until it has been ended, this is done by running memtest without any numerical specification like so:
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.
General System Testing Routine
Testing RAM with memtest should be considered part of a multi-step process of performing general system tests. This should also include running Disk Utility to check hard disk health which is done by verifying hard drive functionality and repairing any problems that are found, and also performing a general stress test on the processor and fans by placing a Mac under heavy load. These are all decent methods to perform general system testing, and are particularly worthwhile to do after upgrading elements like RAM or a hard disk, or replacing hardware, whether for troubleshooting purposes or as part of an upgrade path.