Memory issue with old PE 1750

Question

Has anyone else seen a situation where a PowerEdge 1750 refuses to accept a full 8GB of RAM? I have a system that's been fully upgraded to BIOS level A12 (latest), and in which everything else works correctly. It started off at 2GB (4 512k sticks), and I swapped the first bank for 2 GB sticks to make 5GB. That worked fine, but then swapping bank 2 to 2x2GB (maxing out the machine at 8GB) causes the machine to reset itself as soon as it completes spinning up the SCSI disks.

I've tried several different sets of modules, all Registered/ECC and the correct spec, but none work. There appears to be nothing wrong with bank 2, since I can put the 2GB modules in there along with 512k in bank 1, and the system boots. It's just that it fails at 8GB (Windows 2008 32 bit is installed). I heard from one source that setting the integrated USB to non BIOS support might help, but that didn't work.

Any ideas appreciated.

NowSol · Accepted Answer

Hi, I had the same problem and have a solution.

In the bios there is a redundant memory slot setting. By default it is set to disabled. Setting it to enable allowed the server to boot properly and make all 4 slots available to the OS.

I am able to run Windows Server 2008 (x86) Enterprise with 8GB of ram.

Entil_Zha · Answer

Well, the DIMMS have to go in as pairs. I've already done swaps to test each pair independently, and they all work fine in the first two slots. In fact, I can put the 512k units in bank A and the 2GB units in bank B, or the other way around, and it works fine (5GB). It's only the 8GB config that doesn't work.

Units I have are 2048MB PC2100 ECC REG, so the correct spec for the system. And the OS is indeed 2008 Enterprise, so it should address that much RAM.

Already tried clearing NVRAM...no joy. Almost wondering if PAE in Windows has anything to do with it, but it works with 5GB (already above the PAE limit) so that seems doubtful.

theflash1932 · Answer

Does each DIMM work when installed by itself in the first slot (just to confirm they all work)?

Mind posting the specs of each 2GB DIMM?

You might try clearing the NVRAM using the jumpers on the motherboard.

Also, what version of 2008x86 are you using? ONLY Datacenter and Enterprise can use more than 4GB, and while having more will not usually cause the system not to boot (will usually show 8GB Installed/4GB Usable), it's possible that the OS interaction with the system doesn't know how to handle it.

theflash1932 · Answer

Dell servers support single-DIMM configurations for troubleshooting, but if you have established the health of the DIMM's, then great.

I was going to mention PAE, but thought I'd see which version of Windows you were using ... I agree, if it is ok with 5GB, it should also be ok with 8GB, unless disabled and 5GB is within whatever coded support might exist but 8GB is just too much. You might double-check that it is enabled.

Other than that, based on what you have said, I'm not sure what else it could be. Did you also upgrade the ESM/BMC?

Entil_Zha · Answer

I'll check PAE just to make sure.

ESM was just updated to A37 (1.38, I think) and had no effect. What is BMC? If that's the backplane, it's at 1.08 (I think) and I don't believe there's a higher release. Any idea what that would be listed under in the drivers area?

Very odd problem...

Entil_Zha · Answer

Just checked...PAE is in ForceEnable mode, so it's not that. Checking for other driver updates, but it appears most of the other updaters won't run under 2008. Will need to put a copy of 2003 on a disk just to try this out. Any other ideas appreciated.

GordonRegar · Answer

One could boot from a Fedora 20 Live DVD with the 8gb ram installed and see if that works. (I had to borrow a DVD Drive from a PowerEdge 1950 Server as the 1750 had a CD drive)

PowerEdge Hardware General

Memory issue with old PE 1750

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