Mac Pro not recognising 2nd DIMM Riser

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Mac Pro not recognising 2nd DIMM Riser

I've just installed a total of 10GB RAM in my Mac Pro.

2x 1GB (default) + 6x 2GB

DIMM Riser A is configured with 2 1GB & 2 2GB sticks.
DIMM Riser B is configured with 4 2GB sticks.

System Profiler is showing DIMM Riser A as OK, but showing DIMM Riser B as empty.

It is therefore only recognising a total of 6GB of RAM.

What do i need to do to resolve this?

I've taken out Riser B several times and replugged in the sticks but to no avail.

thanks.

Mac Pro 8-core, Mac OS X (10.5.2)

Posted on Apr 8, 2008 4:19 AM

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Answer 1

The hatter

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61,031 points

Apr 8, 2008 4:35 AM in response to Paul Mock

Try with just the new RAM, or 4 x 2GB on Riser A.

Try with mixing the same on both Risers (2 x 2GB on each Riser in slots 1 and 2 on each).

Confirm that those 4 DIMMs work and show up.

Try with Apple DIMMs on B. And 4 x 2GB that you confirmed work on both, on just Riser A.

Continue until you know if it is a DIMM, a mix of Apple and 3rd party. Or Riser.

Run Apple Hardware Test.

Include the make and vendor.

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Answer 2

Paul Mock Author

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Apr 8, 2008 5:44 AM in response to The hatter

Thanks for the reply.

I've now swapped around the RAM sticks and have not found any to be faulty.

System Profiler is saying that under Diagnostics:
Power On Self-Test:

Last Run: 8/04/08 10:40 PM
Result: Failed
Failure type: Memory
Memory slots: DIMM 1/DIMM Riser B, DIMM 2/DIMM Riser B

How do I run Apple Hardware Test?

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Answer 3

The hatter

Level 9

61,031 points

Apr 8, 2008 5:59 AM in response to Paul Mock

Not faulty and still not recognizing the full amount installed?

Also, FBDIMMs get hot, so hot that you really want to wait 15 minutes before opening the case and handling them.

Most Apple support articles can be found here.
http://www.apple.com/support/macpro/

Your Mac came with a mini-booklet. Your DVD Installer has AHT and directions on the label.

Install iStatPro or Hardware Monitor to monitor RAM, cpu and disk drive temps.

Who did you buy your memory from?

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Answer 4

Paul Mock Author

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Apr 8, 2008 6:03 AM in response to The hatter

yeah still not recognising the 2nd riser.

i've now swapped out the 2 original 1GB sticks and put in 2 more 2GB. so it's running on 8GB. should be a total of 12GB (i calculated it incorrectly before)

i got the RAM from OWC.

Model:OWC64FBMP2GB

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Answer 5

Paul Mock Author

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Apr 8, 2008 6:27 AM in response to Paul Mock

i'm running AHT now, but strangely under Hardware Profile, it noticed the 2 1GB sticks in riser B. But was saying after it probed the machine that Riser B, slots 1 and 2 were ready for testing.

Now the hardware test appears to be hanging.

it has passed 1 test (test time 10secs) but has not progressed any further for the last 5 mins.

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Answer 6

Apr 8, 2008 6:36 AM in response to Paul Mock

it has passed 1 test (test time 10secs) but has not progressed any further for the last 5 mins.

In Extended Test mode, it can go for more than an hour without the progress bar moving when testing memory.

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Answer 7

Paul Mock Author

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Apr 8, 2008 7:08 AM in response to Malcolm Rayfield

i hadn't put it in extended test mode.

anyway it's really late here past midnight.
will try again tomorrow

thanks for your help so far.

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Answer 8

The hatter

Level 9

61,031 points

Apr 8, 2008 7:28 AM in response to Paul Mock

It should not have taken more than 15 minutes.

You said you swappped RAM around, that meant to me that it showed up properly in System Profile and registered the proper amount in each of the DIMM slots.

First step is to rule out that the new RAM is the problem, or the Riser, or that is conflicts with Apple's RAM.

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