Incorrect / missing RAM

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Level 1

8 points

Incorrect / missing RAM

I have an older model Mac Pro which was purchased with 26 Gigs of RAM, this has always been shown as well on the About this Mac screen. However a few weeks ago I noticed it was only showing 16 gigs as being installed. Then more recently this dropped to only 8. I haven't installed any new RAM or even touched it. The system is running good with no unexpected shut downs. Just wondering why the RAM would be decreasing and if anyone else had a similar problem.

Mac Pro, OS X El Capitan (10.11)

Posted on Aug 31, 2016 9:16 AM

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Answer 1

lllaass

Level 10

210,519 points

Aug 31, 2016 9:30 AM in response to Baje300

What model Mac Pro?

https://support.apple.com/en-us/HT202888

The memory in the 2006-2008 MPs run hot and fail with time. WHen they fail the disappear like you are seeing.

The MPs use ECC (error correcting code) memory ands memory errors are typically corrected and that is invisible to the user. When you get too many errors the pair of memory modules is taken off line. Sometimes that also cause a kernel panic.

Sometimes reseat the modules and the memory riser board (2006-2008) will resolve the problem. But sometimes that is only a temporary solution

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Answer 2

Baje300 Author

Level 1

8 points

Sep 1, 2016 6:46 AM in response to lllaass

Thanks for the reply and advice. Seeing they fail with time would that mean that even if I replaced them completely with a new set this would happen again in a few months or less? As this has dropped from 26 to 8 in the space of about a month.

I'll also try to reseat them today and see if it changes anything.

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Answer 3

lllaass

Level 10

210,519 points

Sep 1, 2016 6:51 AM in response to Baje300

Typically it takes years for good RAM to fail. You may have an additional problem associated with the Memory like a slot or riser-card problem

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Answer 4

Baje300 Author

Level 1

8 points

Sep 1, 2016 8:44 AM in response to lllaass

hmmm hopefully it's not too big of a problem. I've just removed both risers and placed them and it's now gone up to 10 GB. Also just realized each riser has 2 different types of RAM.
Think it'll be a good idea to try replacing the risers and starting fresh with RAM?

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Answer 5

lllaass

Level 10

210,519 points

Sep 1, 2016 11:28 AM in response to Baje300

The modules without the large heat sink (lower photo) are not intended for a Mac. There are for PC servers when they use high airflow to cool them. If you ever heard a PC server operate they are loud because of fan noise.

The high temps will hasten the failure of the modules

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Answer 6

Baje300 Author

Level 1

8 points

Sep 1, 2016 11:29 AM in response to lllaass

Ahh ok thanks very much... That quite possible could be the cause of this problem. I'll be sure to order the correct ones for it today.

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