How much does a non-optimal memory configuration affect performance?

Question

I own a Dell PowerEdge R910 server, and recently decided to upgrade my memory. My goal is to have 1TB of RAM, by installing thirty-two 32GB modules. Doing so would allow me to upgrade to 2TB, in the future.

While searching for these 32GB modules, I had a little trouble finding a single vendor who had 32 of them, in stock, at a good price. So I ended up buying different quantities from different vendors, but made sure that the specs, for the modules, are the same.

After installing them, I receive a message which states that "memory configuration is not optimal". I'm advised to use the same type of modules, for all memory risers, in the machine.

All modules are recognized, and I clearly have 1TB of working memory. Now I'm wondering, to what degree computing performance will be affected, since all memory modules are not exactly identical. Will a performance reduction be significant, or is this something that I don't really have to worry about?

My memory modules were bought from three different vendors. Thirteen came from one, another thirteen came from another, and then I bought six from another. When putting them in the risers, I tried to keep as many similar modules together, as possible. Here's the configuration:

Riser A: 4 from vendor A

Riser B: 4 from vendor A

Riser E: 4 from vendor A

Riser F: 1 from vendor A, and 3 from vendor B

Riser C: 4 from vendor B

Riser 4 from vendor B

Riser G: 2 from vendor B, and 2 from vendor C

Riser H: 4 from vendor C

All of these modules are 32GB DDR3 RDIMM 1333MHz ECC Registered, 4Rx4.

I mostly just want to know if I have to worry about significant performance issues, since I bought these from different vendors.

Thanks for reading my post. I look forward to any insight that anyone is willing to give.

evansste · Answer

Riser D has 4 from vendor B.  I tried to edit my post, but am unable.

evansste · Answer

Thanks so much for your response.

I just checked, and my BIOS version appears to be pretty old. It's version 1.2.2. I'll updated it, right away.

When you say that the configuration is unsupported, are you talking about the fact that I'm using 32GB modules?

Thanks, again, for your response.

DiegoLopez · Answer

Hello @evansste,

Thanks for your email. It was very clear to read and to understand

Well... there is something you need to know about this that can make it difficult to answer. You are now moving on an unsupported configuration. The problem with unsupported configurations is that is difficult to know what will happen: will this affect performance? will cause problems whith the automatic memory error corrections?

It's difficult to know. You may not experiencie any issues or you may. It is not possible to know.

What BIOS version do you have? Make sure to be up to date.

Regards.

DELL-Charles R · Answer

Hello evansste,

I would work on stepping up the BIOS since your version is very far behind then check if you still have the "memory configuration is not optimal" message.

https://dell.to/3smZ1ij

BIOS 2.12.0

Start with one from each year until you are able to apply 2.12.0

Bottom of the page > Other Available Versions

2.11.009 -Apr 2018

2.10.025 -Nov 2013

2.9.023 -Sep 2013

2.8.218 -Dec 2012

2.7.709 -Oct 2012

2.7.426 -Jun 2012

2.7.009 -Apr 2012

2.5.005 -Dec 2011

evansste · Answer

Well, I started this process of updating the BIOS, and an odd thing has happened. It seems that the newer versions seem to be less compatible with the new hardware, than my original version.

I updated my BIOS to version 2.5.0. However, after rebooting the computer, it couldn't recognize the 32GB memory modules. The system halted, and reported a message which read that the system could not detect any memory.

So I took out all of the 32GB modules, and put in 16GB modules. I put a 16GB module, in every other slot, so that the system would result with a total of 512GB of memory. The system booted up with no problems.

I then tried to update the BIOS to version 2.7.0, and received the following error message when trying to run BIOS program "R910-020700C.exe".

Illegal Instruction occurred

CS=04E1 IP=0531 SS=2585 SP=4DA6 DS=0009 ES=2585

EAX=00103880 EBX=00010000 ECX=00002585 EDX=00000211

ESI=00000082 EDI=00004EEE EBP=00004DCC

Opcodes @CS: IP 2E 0F 01 16 F0 04 0F 20

Aborting program

I get this same result if I try to run any of the following BIOS programs:

R910-020900.exe

R910-021100C.exe

R910-021200C.exe

It makes sense that updating to the latest BIOS would only improve matters, but I'm beginning to think that I should have stuck with BIOS version 1.2.2.

Any ideas why I'm running into this problem when trying to update from 2.5.0 to 2.7.0?

Because a lot of those letters look like internal processor registers, I'm wondering if the newer BIOS doesn't like the processors. The machine has four X7560 processors. According to the R910 specification sheet, these should be fine.

I suppose what's really worrying me, is that the Dell website doesn't seem to have BIOS version 1.2.2 for the R910. The oldest seems to be 2.5.0. So if I wanted to revert back to 1.2.2, how would I do it?

If anyone has any ideas as to why this may be happening, and how to fix the problem, I'd love to hear from you.

Dell-Martin S · Answer

Hi,

could it be possible that this was a non-official Version only for your company because I could not find this BIOS Version in our Database?

If yes you could contact your technical account manager to get this special BIOS version.

Regards Martin

evansste · Answer

Thanks for your response, Martin.

I bought this server, used, on Ebay, years ago. So, unfortunately, I don't know what the original company did, or how they operated.

I was able to finally get the latest BIOS, version 2.12.0, to install. Unfortunately, it too, gives me a message stating that it doesn't recognize any memory.

I have some M910 blade servers. I put some of the 32GB modules into one of those, and it recognized the memory, and booted, with no problem. That server has BIOS version 2.10.0, I believe. I'm going to try installing that version on my R910, and, hopefully, it will then recognize these 32GB modules.

evansste · Answer

I just installed BIOS version 2.10.0 into the R910, and it doesn't work. Version 2.10.0 won't recognize 32GB modules in the R910. However, it will recognize them in the M910.

I should also note that, in the M910, I still get the message about memory not being optimal. It's the same message that I saw with BIOS version 1.2.2., in the R910. So, I'm not sure that there's any way to make that message go away.

Anyway, at least the modules are recognizable in the M910. I just wish there was some way to get version 1.2.2., installed back onto the R910.

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How much does a non-optimal memory configuration affect performance?

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