How do I check my Mac's RAM?

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?

Solution 1:

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: http://osxdaily.com/2011/05/03/memtest-mac-ram-test/

Solution 2:

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.