I have a MacBook Pro (mid 2012) and I have changed the hard disk to a Crucial_CT250MX200SSD and changed the RAM to CRUCIAL CT8G3S160BM. My Operate System is OS X 10.11.4.

First, I found sometimes my Mac wouldn't wake after sleep and I have to force it to restart. Then after sometime, I found it even couldn't start: black screen with 3 alarms. Sometimes it could start after I tried again, but sometimes it wouldn't.

I have tried to change the RAM back to the original but the problem still appeared. The Genius Bar couldn't found the problem, neither.

This problem usually happened after I put it in my backpack and travel to a different place. So could it be caused by vibration? Actually, when it wouldn't start, pulling the RAM out and reinstalling it could help.

Does anyone have met similar problems? What may be the problem of my Mac? Thank you!!

edit (2017.1.26)

AHT results:

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Figure. 1 Figure. 2

  • It sounds like you have a hardware issue. First thing to do is run Apple Hardware Test (AHT). Hold the D key while booting from a powered off state with the AC adapter connected. Update your question with the results by editing your original question.
    – Allan
    Jan 19, 2017 at 13:26

2 Answers 2


3 beeps upon startup definitely signals a RAM issue. The problem is that most people assume that only the actual RAM itself can trigger the beeps when in fact there's a chance that it could be the RAM slots causing the issue.

What you're describing to me sounds a lot like a possible solder point issue between the RAM slots and the logic board itself, unfortunately. What leads me to believe this is 1) you've tested multiple sticks of RAM and the issue still occurs, 2) you believe it's happening after transport so things could be shaking loose temporarily, 3) the genius bar couldn't find an issue when running tests meaning maybe when they were testing it the weary solder points just happened to have settled and were making sufficient contact at the time.

Since the genius bar proved to be of no help I would strongly recommend something called an Apple Authorized Service Provider for a second opinion. You can find one using this link (click on the 'Service' block):


Not to bash Apple Stores but they're busy places. I would try a non-Apple Store location this time as they aren't as busy and aren't trying to shuffle you out in a set period of time to get to their next appointment. They'll likely spend more time with your machine hands-on to get to the bottom of it.

  • Thank you for your answer. Your analysis seems convincing. Can I ask the non-Apple Store to look at my RAM slots specially?
    – Zhiyang
    Jan 19, 2017 at 7:52
  • I don't see why not? AASPs are basically just local computer shops that obtained a license through Apple to diagnose and repair Macs legally. They've been trained and are trusted by Apple from a technical standpoint but from my experiences have a more 'down to earth' vibe. You can usually speak to their technicians by request (although if they're busy in that moment they may have to call you back), they don't just have a genius take your computer to a magical wizard in a back room and then return after a few minutes with it telling you that nothing is wrong.
    – NYKg
    Jan 19, 2017 at 8:14

The first step would be to check out About Mac computer startup tones and identify which one of these startup tones is the one you're experiencing with your Mid-2012 MBP.

Near enough is not good enough! If your startup tone does not match exactly one of the ones listed, please comment back and say so and describe which one it is closest to and what the difference is. Unfortunately, not all of the possible startup tones are listed on that page, but identifying the correct tone helps narrow down your problem!

A possibility?

There was a common problem with some MBP models, but this predominantly affected 13" pre-2012 models. Regardless, there was an issue with logic boards not being able to address the RAM. In many cases it was caused by pressure, over time, on the bottom of the MBP which in turn placed pressure on the logic board.

You could test for this by applying some pressure on the bottom case as you start up or wake the computer. Place the pressure as follows: facing the bottom case, apply the pressure to the centre of the case, but slightly to the right (but not all the way).

If it's slight physical damage such as this, then you'd need a new logic board. However, you could try and manage the situation by always using the MBP on an even surface (such as on a desk). Also, transporting it in your backpack sounds like some sort of trigger, so you may want to pack it in well so that the bottom case is not being 'bumped' by other items in your backpack, as this may affect how well the RAM is sitting in the slots. Finally, you may want to handle your MBP carefully (e.g. don't pick it up / carry it with only one hand).


Now that we've established it's definitely an issue concerning your RAM in some way, we need to try and get to the bottom of what's causing it. Please be patient as troubleshooting is often a process of elimination and can take some time. The next step is to do a general test of your hardware.

Run Apple Hardware Test

Your model MBP uses Apple Hardware Test. To use this, follow these steps:

  1. Shut down your MacBook Pro
  2. Insert your original 2 x 2GB memory modules
  3. Restart your MacBook Pro
  4. Press and hold the D key before the gray startup screen appears
  5. After a while, Apple Hardware Test (AHT) will start
  6. When prompted, select your language and click the right arrow
  7. When the AHT console appears, select the "Perform extended testing" checkbox and then click the Test button.
  8. Your test results will appear in the window in the bottom-right of the console
  9. Take a note of the results
  10. Shut down your MacBook Pro
  11. Now remove one of the 2GB memory modules and repeat steps 3 - 10
  12. Now reinsert the 2GB memory module and remove the other one and repeat steps 3 - 10
  13. Now remove the 2GB memory module and insert the 8GB model in the first memory slot and repeat steps 3 - 10
  14. Now remove the 8GB memory module and insert it instead into the second memory slot and repeat steps 3 - 10
  15. Now insert one of the original 2GB memory modules into the first memory slot and repeat steps 3 - 10

Note 1: These tests will take some time. At completion you should have run the Apple Hardware Test six times. Make sure you record the results clearly so you know what they were for each of the six memory configurations.

Note 2: If pressing and holding the D key at Step 4 doesn't work, start again at Step 3 and, at Step 4 press and hold both the OptionD keys instead. This will try and run Apple Hardware Test from the internet instead, so you will need to allow more time for it to complete.

  • Thank you for your answer! First, the tone is the 2nd kind: "3 successive tones, a 5 second pause (repeating): This indicates RAM does not pass a data integrity check." And I tried to apply some pressure and even knock the bottom case. But the problem doesn't appear. It seems not so easily to be triggered. But as I use my Mac in my daily life, no severer impact is likely to be applied to the computer.
    – Zhiyang
    Jan 19, 2017 at 7:54
  • That's a good sign that it's not easily triggered, as it suggests your MBP isn't suffering from the logic board/bottom case issue. Can you advise the exact details of your model MBP and how much RAM you had originally and how much you had after the upgrade? I will then update my answer with some other steps for you to try.
    – Monomeeth
    Jan 19, 2017 at 10:42
  • Ok, the RAM originally is 2+2GB. I bought a 8GB Crucial RAM. Actually I have tried to use the original 2+2GB and 8+2GB. In these cases the problem all appeared. Other details: MD101 (13inch, mid 2012), CPU: 2.5 GHz Intel Core i5. For OS, I met this problem when it was OS X 10.11.6 and now I upgrade to 10.12.2. The problem still appears. Thank you very much for your earnest help!!
    – Zhiyang
    Jan 19, 2017 at 11:24

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