Cannot get all memory Modules to be recognized

Question

I purchased a refurbished PowerEdge R720 that had 64GB installed (8x8GB).

I have since purchase an additional 4x 8GB Memory Modules (ECC Registered DDR3) and am trying to get them installed so that I have a total of 96BG split evenly between the two CPUs.

Looking at the chart I found on the Dell Support website, it seems these are the slots that should be populate:

So I have made sure I have a DIMM installed in each of those slots. But unfortunately, only 80GB is being detected. two of the DIMMs are showing in iDRAC but are not counting (you can see they show 0GB) and for some reason some are showing Info not Available instead of the "DDR-3" indication.

What am I missing here?

Thanks!

DELL-Young E · Answer

Hi, thanks for choosing Dell. I think what we need to determine first is whether the fault lies with the memory or the slot.

Also you can refer to this article: https://www.dell.com/support/manuals/en-us/poweredge-r720/720720xdom/sample-memory-configurations?guid=guid-afe58651-3836-4641-8d7b-463afac05ea6&lang=en-us

DELL-Shine K · Answer

Is the new 4 memory module from Dell? You can try below steps and check the behavior Update BIOS and iDRAC to latest Swap the memory to a working slot and check whether the behavior follow the DIMM or the slot. If behavior follow the DIMM it could be a DIMM problem Try booting with only A1 and B1 populated with new memory and check the behavior

tokenwizard · Answer

Aren't there specific slots that have to be occupied in order? I was afraid I was adding the DIMMS in the incorrect slots, but per the chart I referenced, it seems correct. So I will follow standard RAM troubleshooting techniques as you suggest, while trying to mitigate downtime.

tokenwizard · Answer

Yes, That is the chart that I attached a screenshot of in my original post. I have 12 DIMMS in the slots indicated in that chart. Two of them are not registering as you can see in the iDrac screenshot in my OP.

I am going to try swapping some DIMMS around and see if the problem follows them.

tokenwizard · Answer

Still not having any luck with this. I did swap the memory B3 and it seems to be detecting the new stick.

I have slots A1-6 and B1-6 populated for a total of 12 sticks. Each is an 8GB stick of PC3-10600 2Rx4 1.5v ECC RDIMM.

During POST, the server recognizes 96GB of installed memory:

But in iDRAC, it still only shows 80GB installed, with two of the sticks being detected but not initialized:

According to the chart in the above link, slots A1-6 and B1-6 are the ones that need to be populated for 12x8GB DIMMS. If in fact A6 and B6 slots are dead, is is possible to move those two DIMMS to different slots? If so, which ones?

EDIT:

Proxmox does seem to see the 96GB of Memory, too. So is this just a bug in iDRAC?

PowerEdge Hardware General

Cannot get all memory Modules to be recognized

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