Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I know there is MemTest86+ for PCs, but what can I use to see if my RAM is actually good in an Apple product? Whether it's a MacBook, MacBook Pro, iMac or Mac Pro? What symptoms would show that RAM is bad?

share|improve this question
If you have bad RAM, your computer probably won't boot successfully. – Nathan Greenstein Sep 12 '11 at 23:34
I had an iMac G5 that booted for months with bad ram. The symptom I saw was infrequent (but more than I was used to) kernel panics. I finally associated the panics with my having installed a memory upgrade. (I can be slow). Confirmed bad module (using Rember), swapped with vendor, never saw another panic—or not so as I remember, – jaberg Jan 25 '12 at 18:48
up vote 5 down vote accepted

I've had bad RAM that still allowed the machine to boot - a stick of memory in my Mac Pro apparently failed gracefully overnight.

The first step would be to check system profiler to see if the memory is being recognized. If indeed it is, there's a version of MemTest for OS X:

share|improve this answer
Thanks, that's the type of thing I was looking for – Canadian Luke Sep 12 '11 at 23:58

Kernel panics, the black screen & beeps (referenced elsewhere), or weird crashes that you can't attribute to anything else all can be caused by bad RAM.

I use Rember which provides a GUI interface to Memtest. It was suggested to me by a tech support rep at One World Computing as their approved way of checking for a bad module before returning ram for exchange. I didn't want to waste their time and resources if my problem, periodic kernel panics, wasn't, as I suspected, caused by a memory upgrade. It turned out that the memory was to blame.

Memtest and Rember will sometimes find problems that Apple's Hardware Test won't and I highly recommend using one of them if you're looking for bad memory modules.

share|improve this answer

Some signs of bad RAM also include black screen 3 beeps in 5 seconds, this may happen continuously, You can use the method that EpiGrad mentioned or alternatively you can test it with Apple's Hardware Test, if you still have the OSX Disc, insert disc, hold down d on start up memory test should be one of the main categories listed, unless it has been updated since i last used it.

share|improve this answer

It's not as exhaustive as MemTest and Rember, but there's a userspace utility called memtester. You can call it by using memtester 4G. Call memtester to see other options as well.

You should also be able to call memtest86 from a LiveCD for Ubuntu or most other operating systems. Give it a try.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.