Early Mac Pro does not recognise ram in Riser A

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Level 1

4 points

Early Mac Pro does not recognise ram in Riser A

System information shows that I have only 8Gb of ram installed when it should show 14Gb, there appears to be no ram installed on Riser A even though I have 6 GB of ram on the card. Assuming that the issue was the card on which the ram was installed I swopped the card from Riser B which has the 8Gb on and put it in Riser A and the 6Gb in Riser B. System Information now shows that only 6Gb is installed so I think it can be assumed that the cards and the ram chips are OK. So is this a hardware or software issue?

I recently had to replace the Grphics Card as the old one died could this have resulted in some damage to the motherboard.

Mac Pro (Early 2008), OS X Mountain Lion (10.8.2)

Posted on Feb 9, 2013 5:32 AM

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Answer 1

Johnb-one

Level 6

9,156 points

Feb 9, 2013 12:23 PM in response to Bad Ram

all I can give you is my 2cents. I have the same kind of Mac pro you do, and here's what did it for me: There is a certain way to install the Ram modules, the mac pro "prefers' it like that. Usually matched pairs. You could also try memtestosx.org

here is a link to apple's installation diagram

http://manuals.info.apple.com/en/MacPro_Early2008_MemoryDIMM_DIY.pdf

maybe the riser is bad, but that could be premature...I may be wrong

anyways, follow the diagram and you may be successful... I think you may have to shut down the Mac pro before swopping risers.... then again, you may have bad ram, or not

JB

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Answer 2

Bad Ram Author

Level 1

4 points

Feb 11, 2013 5:15 AM in response to Johnb-one

Thanks for the response, however the Ram on both cards is recognised when installed in Riser B but neither card is recognised in Riser A as I pointed out in my first post. Which would suggest that the problem lies with the Mother Board / Riser connection. I also mentioned that I recently had to swop out the Graphics Card as the original had died is there a connection from Riser A that could have been dislodged during installation og the new card? I suppose I'll have to take the thing apart and have a dig around.

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Answer 3

The hatter

Level 9

60,990 points

Feb 11, 2013 6:40 AM in response to Bad Ram

The top slot for a Riser then, even after replacing with a new one?

And where did you buy the new Riser?

Whose RAM?

What graphic card? you had 7300GT and put an ATI 5770 in and connected the power cable w/o trouble?

DVWarehouse is one of two places I am aware of that sells quality Mac Pro parts.

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Answer 4

Bad Ram Author

Level 1

4 points

Feb 12, 2013 2:56 AM in response to The hatter

What graphic card? you had 7300GT and put an ATI 5770 in and connected the power cable w/o trouble?

No, had some power issues, computer would randomly shut down to begin with but after a full SMC reset the ATI 5770 has been fine.

The top slot for a Riser then, even after replacing with a new one?

And where did you buy the new Riser?

Have not replaced either of the risers?

Ram is a mix of Crucial and Kingston and was all working prior to Graphics Card being replaced.

OK! So I have run a Hardware test which shows I have all 14Gb of Ram physically installed in the appropriate risers but only 8Gb is shown to be actually working. Thats the 8Gb installed on the card in Riser B. Can anyone explain that?

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Answer 5

Bad Ram Author

Level 1

4 points

Feb 13, 2013 3:21 AM in response to Bad Ram

Apologies, I think I may have confused the issue somewhat with my incorrect use of nomenclature. When I referred to the Riser I thought this was the socket, I now realise that the term Riser refers to the Card on which the ram is installed.

So just to recap both Riser Cards work, as does the Ram installed on them, however when either of the riser cards are installed in the top socket they are not recocognised. So the problem in all likelihood is a dodgy socket A!!!

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