The RAM in your Mac is in essence the active workspace of your computer, in which your programs run and your content is created. Because of this, healthy RAM is vital for properly running any software on your Mac, be it the system software that comes with OS X or third-party programs.
Unfortunately, if the RAM in your Mac is faulty, those faults can sometimes persist undetected for a while, only to crop up unexpectedly and result in a crash, hang, or other unwanted behavior. Therefore, it is good to not only be able to identify faulty RAM, but also be able to properly test for it and then be prepared to fix the problem, if it arises.
Faulty RAM symptoms
If your system's RAM is not working correctly, then you will likely see one of several symptoms when using your Mac:
Random Application Crashes: If programs randomly quit unexpectedly, and the generated crash report shows different potential reasons for the crash, this may indicate bad RAM.
Random Pauses: When a background task is addressing bad memory and is crashing, it may cause the system to continually re-launch it or otherwise hang up when attempting to use this task's services.
Data corruption: If files you save or access regularly become damaged and cannot be opened, it could be corruption in your filesystem formatting — but it could also indicate faulty RAM.
Random kernel Panics and system freezes: This may happen when core OS components attempt to access bad RAM and crash, resulting in a kernel panic or the system immediately halting.
Three beeps from your Mac at startup: Before the boot chimes sound at startup, your Mac will run a rudimentary check to ensure RAM is available and accessible. If not, then you will hear a series of three beeps from your system, and no boot chime. The system will also not boot when this sound is played.
Other inabilities to boot your system: If you cannot get your system to boot, and especially if you don't hear the boot chimes, this may suggest RAM is not accessible, and some fault is preventing the system even from issuing the three beeps warning.
While these symptoms suggest faulty memory as a possibility, keep in mind they may not necessarily occur regularly: They may instead happen only when the specific faulty areas of your installed RAM are accessed, the frequency of which may change depending on the amount of RAM installed and how much you use it, which will govern how often the faulty areas of RAM are accessed.
Testing your RAM
If you are experiencing some symptoms that suggest faulty RAM, then there are several ways to test your Mac's RAM and ensure it is healthy and available.
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