Resolved Memory Slots Showing As Empty?

[The Buggman]

Hello All,

I recently upgraded to OS X 10.9 before installing 2x2GB of memory into my Early 2008 Mac Pro which would make for a total of 10GB RAM.

The configuration involves splitting the original 2x1GB – one on each side and into slot 1 – with the new 2x2GB memory in slots 2 and 3 on each side.

However, for some reason, as I check my total RAM, it shows as only having 6GB of memory. Additionally, as I check System Information, the second memory slots for both sides are showing as empty.

Is this something I've caused with my configuration or would this entail a bigger issue? I have included a screenshot to show my problem. DIMM2 in Riser A and B should both be showing and additional 2GB.

http://i.imgur.com/FYv7aLD.png

 

[photographypro]

move the chips

Moving the "empty" chips to different slots. If they show as "empty" in their new locations, they're probably bad.

 

[The Buggman]

I've tried swapping the sticks already. If there's nothing of which I'm unaware that would cause these slots to show as empty in this configuration, I can only imagine the slots themselves are bad. But, it's a little too coincidental.

Both of the second slots on each side certainly wouldn't suddenly go bad. Also, both 2x2GB sets of RAM were purchased separately. The original set occupies one side and the new set occupies the other.

I could try moving the sticks from slots 2 into slots 4. Would that cause any unforeseen troubles?

 

[westrock2000]

Attaching working image

Hello All,

I recently upgraded to OS X 10.9 before installing 2x2GB of memory into my Early 2008 Mac Pro which would make for a total of 10GB RAM.

The configuration involves splitting the original 2x1GB – one on each side and into slot 1 – with the new 2x2GB memory in slots 2 and 3 on each side.

 

[westrock2000]

When I first got my Mac it had 2x512MB and 2x2GB and I tried the same thing you are doing to see how the risers worked and the same thing happened. In my case I did 2GB+512MB on each side.

You have to keep like values as pairs. So put one pair of 2x2GB on each side. And then put the 2x1GB on one side (doesn't matter which). It should work after that.

 

[DanielCoffey]

According to Apple on http://manuals.info.apple.com/MANUALS/0/MA430/en_US/MacPro_Early2008_MemoryDIMM_DIY.pdf

The Mac Pro (Early 2008) computer has two memory riser cards with a total of 8 memory slots. On each card, the slots are arranged as two banks of two slots each. The computer comes with a minimum of 2 GB of memory, installed as a pair of 1 GB fully buffered, dual inline memory modules (FB-DIMMs) in two of the DIMM slots. Additional pairs of 1 GB, 2 GB, or 4 GB FB-DIMMs can be installed in the open DIMM slots, as illustrated below. Maximum memory is 32 GB.
DIMMs must be installed as pairs of identical size and type, from the same vendor.

So you will want 2 + 2 + 1 + 1 and 2 + 2 + empty + empty

 

[The Buggman]

Thanks to all who replied.

After trying several different configurations with various results (going from showing 6GB to 3GB to 6GB and then to 8GB), I believe I have determined that the original 2x1GB are no longer compatible with the extra 2x2GB in place. I now have 2x2GB on each riser.

None of the memory is corrupt, but I believe I must retire the original 2x1GB and settle on 8GB of total memory instead of the desired 10GB... (unless I end up with a second pair of 1GB sticks to even out each side). Thanks again for your assistance.

 

[DanielCoffey]

Did you follow the illustration for which slots to use when you have 6 dimms?

 

[The Buggman]

I did. I know the sticks to be functioning, but the 2x1GB were failing to be recognized. I'll definitely try again in a bit, however. I cannot remember if they were occupying slots 1 & 2 or 3 & 4. Perhaps that will be what makes the difference[?].

 

[DanielCoffey]

It should, yes - the guide was quite specific.

 

[The Buggman]

Well I would love to have come back and said how there's no way it was my fault. I would have mentioned how the guide fails to speak of the importance of size order in the risers' slots and spoke of how I, alone, outsmarted the machine in triumphant determination.

Unfortunately, none of this is true. There is no importance to size order when pairing the slots on the risers. The blunder was my own. In my early-morning ineptitude, I did not fully regard the difference between Riser A and Riser B. Thus, the issue has been resolved as provided by the obligatory RTFM platitude.

Thank you for your persistence and devotion to the matter, DanielCoffey.