"Errors detected on memory module"

Question

"Errors detected on memory module"

I have an Early 2008 Mac Pro (3,1) running OS X 10.10.1 with the original two 1GB modules. Then I added two 4GB modules. I just discovered that under System Information > Memory, one of the 4GB modules has the yellow triangle with the exclamation point in it and the module is grayed out. At the bottom it has the same symbol and says "Errors detected on memory module."

When I run Remember (the GUI for memtest), it tells me that "All tests passed!" However, with nothing else open it says that my available memory is 3121MB and that's the memory allocated for testing. This is in spite of the note saying that "Total built-in memory: 10GB."

All this leads me to believe that it didn't even test this 4GB module because it has errors. Could someone confirm this? Thank you.

Mac Pro, OS X Yosemite (10.10.1)

Posted on Jan 23, 2015 9:18 AM

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Answer 1

Best reply

lllaass

Level 10

210,411 points

Jan 23, 2015 9:23 AM in response to orchestramusic

Try cleaning the slots and contacts of the memory and reinstalling them.

Try different slots.

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Answer 2

Jan 23, 2015 9:37 AM in response to orchestramusic

The Mac Pro 42 lb silver tower and black cylinder feature Memory Hardware Error Detection and Correction. This hardware is used during the Power-on self test. If any errors, correctable or not, occur in the first few seconds of testing, the module is [rightly] declared BAD, and should be replaced. So the answer to your direct query is, "Yes, the module WAS tested -- at full speed and checked by the Hardware, and found to be Bad in under a quarter minute."

Memory problems are very difficult to isolate. Your Mac has handed you the information about which module is Bad. You should rely on it. Your testing is complete, the Bad module has been identified, and no more testing is needed.

Return the Bad module to the vendor for replacement, or buy a new module. In the 2008 model, return the PAIR, as either one could be Bad, and it is not your responsibility to figure out which one.

It is a good practice in general to test the new modules by themselves (as a pair by itself in this case) before testing with other modules. This gives you assurance going forward that the modules may be good without muddying the experiment with possible module mixing issues.

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