How can I tell which RAM dimm is faulty?

Question

Level 1

29 points

How can I tell which RAM dimm is faulty?

Hi and thanks in advance.

I have a late 2012 27-inch iMac. 2.9 Ghz Intel Core i5; 16 GB 1600 mHz DDR3; Nvidia GeForce GTX 660M 512 MB

I'm pretty sure that I have a bad RAM dimm. But How can I tell which is the failing one?

Background: My computer was hanging up; Shutting down; crashing. At one point, I couldn't even get to the log-in screen. I ran the diagnostic and it said something like mem/61/ error:

I removed one of the dimms (the bottom one) and my computer finally started! Yay! But when I ran diagnostics again, it said that at still had a memory error. This leads me to believe that yet another dimm is truly the culprit or the diagnostic program thinks that an empty bay is an error. Then again, it seems that since my computer started happily without one of its dimms, I have discovered the bad memory card.

I'm not sure how to proceed. Any advice you may have would be very much appreciated. Thank you.

Jon

iMac (27-inch, Late 2012), macOS Sierra (10.12.5)

Posted on Jul 2, 2017 8:25 AM

Reply

Answer 1

den.thed

Level 10

90,946 points

Jul 2, 2017 7:14 PM in response to Jon Hand1

On your menu bar go to: Apple > About This Mac > click on System Report... > then click on Memory in the Hardware section.

There you should be able to see which 0x805b2d90 module has failed and which slot it is installed in.

Reply

Answer 2

Jon Hand1 Author

Level 1

29 points

Jul 3, 2017 5:38 AM in response to den.thed

Thank you for your help. Nothing seems to match up. Perhaps the error is because one of the RAM modules is empty. Perhaps I randomly removed the faulty module the first time. I'll try putting it back in and I'll see what happens. Then I'll try switching them around. I've attached a pic to share. Thanks again.

Reply

Answer 3

den.thed

Level 10

90,946 points

Jul 2, 2017 8:58 AM in response to Jon Hand1

You may just have a loose or unseated module. I would first try reseting all of the modules to see if that solves the problem.

If not, then run the Apple Hardware Test as per > How to use Apple Hardware Test on your Mac - Apple Support

If that does not help to identify the faulty module or slot, then you may need to test each module individually.

Reply

Answer 4

Allan Jones

Level 9

77,912 points

Jul 2, 2017 9:41 AM in response to Jon Hand1

Is this memory yo uadded after purchase or an original Apple RAM module? If you added it later, please tell us the brand and type you ordered. Not all "Mac" RAM works in modern Macs--lots of scamming going on. PNY RAM is often troublesome as are the low-cost "Value RAM" or "Bargain RAM" sold by Kingston and Corsair. Both firms also sell higher quality RAM but its is hard to find because the RAM market is so price-sensitive.

For over a decade I've bought all my after-market Mac RAM from one source--Other World Computing--and have never had an issue.

Reply

Answer 5

Jon Hand1 Author

Level 1

29 points

Jul 2, 2017 10:27 AM in response to Allan Jones

Hi Allan,

The module that I removed was "hynix 4GB 2Rx8 Pc3 - 12800S -11-11-F3. The ram was added at the apple store about 5 years ago when I purchased the iMac. I don't know if this module is the faulty one. Thank you for any insight you might have.

Reply

Answer 6

den.thed

Level 10

90,946 points

Jul 2, 2017 10:40 AM in response to Jon Hand1

The AHT should have indicated the bad one by module # or slot #.

If it did, then go to: Apple > About This Mac > System Report > and select Memory in the Hardware column to see which one is bad.

If not, then you may need to Install and test each module individually to find the bad one.

Reply

Answer 7

Jon Hand1 Author

Level 1

29 points

Jul 2, 2017 6:42 PM in response to den.thed

Hi again!

I ran the AHT again. It said:

The characters mean nothing to me. Can you please translate? Thank you!

Jon

Reply

Answer 8

Jon Hand1 Author

Level 1

29 points

Jul 2, 2017 10:24 AM in response to den.thed

Hi den.thed,

I have already used the Apple Hardware Test. It told me that I have an error with my memory. But it did not tell me which module is the offending one - as far as I can tell.

Reply