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How to test for bad or faulty RAM on a Mac

David Price | May 17, 2016
Worried that your Mac's RAM is malfunctioning? Here are giveaway symptoms and reliable tests that let you check its performance

You can check easily whether your Mac's RAM has stopped working properly, and we'll walk you through those tests in this article. But before we start, bear in mind that the tests are quite time-consuming. Unless your Mac is exhibiting specific symptoms of bad RAM - which we also cover - then we'd recommend running the RAM tests once a year or so.

How to test for bad or faulty RAM on a Mac: Telltale signs that your RAM is faulty

Bad or faulty RAM makes itself known in various ways and at various times. As a general guide, look out for one or more of the following symptoms, but bear in mind that they won't appear consistently: very often a problem will only occur when a particular part of your RAM is accessed.

  • Triple beep on start-up: The clearest signal your Mac can give that its RAM needs to be replaced. You'll hear three beeps instead of the usual startup come when booting up; and then the system won't boot. A failed boot is always a bad sign, but the triple beep lets you know that the Mac detected a RAM issue when running its standard boot-up diagnostic check.
  • Failure to boot: Even if there wasn't a triple beep, failure to boot up may still indicate a RAM problem. If this is happening consistently, it's worth running the test in the next section.
  • Unexpected/unexplained software crashes: An application packing in can be caused by many things, but if this seems to be happening more than normal (and particularly if the crash reports show inconsistent causes) it could point to a RAM problem.
  • System freezes: Also kernel panics.
  • Corrupt files: From time to time you will find that saved files become corrupt, and this is normal. But if it's happening a lot, it could be evidence of faulty RAM.

How to test for bad or faulty RAM on a Mac: How to test the performance of your RAM

The symptoms have allowed us to reach a working diagnosis, but like Gregory House MD we won't be happy until we've got confirmation of the illness. Here's where dedicated memory-testing diagnostic programs come in.

After running the following tests, it's a good idea (if the design of your machine allows this) to swap around the RAM modules in your system and test again. This helps to make sure that all RAM addresses are accessible to the testing program, and thus gives you a more comprehensive set of results.

Apple's own RAM checks

You can easily check the RAM using your Mac's built-in tests. Restart or boot up your Mac and hold D while it boots; this will take you to the diagnostics screen. The Diagnostics section varies depending on the age of your Mac and OS: on older systems (where the diagnostics page has a blue background) you'll need to select the middle tab, Hardware Tests, then put a tick next to 'Perform extended testing (takes considerably more time)' and hit the big blue Test button.


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