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We've recently upgraded the RAM on a Windows Storage Server 2008 R2 Standard to 32 GB.

When I open the System panel, it indicates Installed memory: 32.0 GB (16.0 GB usable). Why is that?

I've been trying to dig up documentation that would indicate that this is a limit of the operating system version, but I've come up short. Looking at the version comparison on Wikipedia shows no version with 16 GB, but Storage Server isn't listed and Memory Limits for Windows and Windows Server Releases doesn't list Storage Serer 2008 R2.

I've since found an infographic in the blog post titled Windows Storage Server 2008 R2 is now available!, which indicates that the limit would be 32 GB.

As suggested by @Nico, opening perfmon shows that 16 GB of memory are "reserved for hardware".

The board of the server is an Intel S3420GPLX set up with an Intel Xeon SP X3430, both of which are supposed to support 32 GB of memory.

The installed RAM modules are 4 x 8 GB Hynix HMT31GR7CFR8A-H9 RDIMM.

Support advised us to perform a firmware upgrade of the mainboard. We performed the firmware upgrade, but it had no effect on the issue

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  • You sure the problem isn't hardware?
    – Zoredache
    Jul 21, 2014 at 6:43
  • @Zoredache No, I'm not sure. But I basically asked our supplier, who we bought the server from, to send us the max amount of memory that the board could handle and they looked up the 32 GB in their database and sent them over. I'll check back with them though.
    – Oliver Salzburg
    Jul 21, 2014 at 6:45
  • Maybe check firmware versions and so on?
    – Zoredache
    Jul 21, 2014 at 6:47
  • @Zoredache I'm trying to get in touch with their support, but it's still pretty early in the morning here. Will update when I get more info.
    – Oliver Salzburg
    Jul 21, 2014 at 6:48
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    technet.microsoft.com/en-us/library/gg214172(v=ws.10).aspx lists the memory limits for the different editions of Storage Server 2008 R2 (none of them are limited to 16GB).
    – Håkan Lindqvist
    Jul 21, 2014 at 20:22

6 Answers 6

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High end servers have options for pairing memory modules, like raid arrays for hard disks. You must view the BIOS option for that.

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  • 4
    This was my thought as well. It's typically labeled as "Memory Mirroring"
    – MDMarra
    Jul 21, 2014 at 15:31
  • While it sounded promising, no feature like that seems to be available in the boards BIOS.
    – Oliver Salzburg
    Jul 28, 2014 at 8:07
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Have you see this link ?

Running a Perfom /res would show you this "bug". Cause the missing RAM might be hardware reserved.

Also, have a look at this Microsoft's KB : http://support.microsoft.com/kb/978610

(I apologize, I cannot add any comment due to reputation)

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  • Yeah, it shows 16 as reserved for hardware. The KB article didn't provide anything I deemed helpful. I'm currently trying to gather information for tech support so that they can determine possible hardware issues. Thanks
    – Oliver Salzburg
    Jul 21, 2014 at 8:20
  • Ok. (Agree that the KB isn't probably the best one) On Google, seems like this is a motherboard issue. But wait for support feedbacks and update your question with their answer if possible. That must help.
    – Nico
    Jul 21, 2014 at 8:25
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It would be useful to know the exact configuration of RAM. i.e. the number of dimms, whether they're all udimm (unbuffered) or rdimm (registered). You can't mix udimms and rdimms on the board, and if you're using udimms you can only use 4/6 of the dimms and can only use up to 16GB of RAM - this sounds a likely cause for your issue.

Reference - https://communities.intel.com/thread/21622

It looks like, in order to get 32GB of RAM working on the board, you need a very specific configuration.

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  • The modules are 4x8 Hynix HMT31GR7CFR8A-H9 RDIMM
    – Oliver Salzburg
    Jul 21, 2014 at 10:48
  • OK - the specs of the RAM look to match the requirements for the board, from the link I sent you people have had issues with RAM that is supposedly supported and have had to change it, but their issues are different to yours ( they can't post ). Have you perhaps tried a linux live cd or similar, to see if another OS will actually boot with all 32GB available?
    – Alex Berry
    Jul 21, 2014 at 10:55
  • I'm actually not on site, but I will do that if necessary. We actually had a set of 4x8GB Samsung Rx4 RAM before and couldn't POST either. :P
    – Oliver Salzburg
    Jul 21, 2014 at 10:57
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In the BIOS, 2 of the modules were marked as "failed".

Support advised us to test every module individually. The tech on-site tested different configurations, then put all the modules back in as they were and now the full 32 GB are usable.

Not really sure what to make of it.

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  • You should have tested with some software other than Windows to determine if it was a software problem or a hardware/BIOS problem. That would have saved you some time and allowed us to rule out Windows immediately.
    – David Schwartz
    Jul 31, 2014 at 9:30
  • Care to name a software?
    – Oliver Salzburg
    Jul 31, 2014 at 9:43
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    memtest86+, Linux bootable CD, ...
    – David Schwartz
    Jul 31, 2014 at 9:43
  • As I explained already, I wasn't on site, otherwise I would have.
    – Oliver Salzburg
    Jul 31, 2014 at 9:48
  • Surely the person who performed the firmware upgrade could have. But whatever.
    – David Schwartz
    Jul 31, 2014 at 9:59
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Many servers have separate RAM for each Processor, so if you have only 1 processor, then you either have to 1) install the 2nd processor or 2) install the RAM in the correct memory channel.

(what hardware server do you have?)

update:

the manual says: 32 GB max with x8 ECC RDIMM (2 Gb DRAM) and 16 GB max with x8 ECC UDIMM (2 Gb DRAM)

the model that you say youhave are RDIMM as far as I can see, but they do not seem to appear on the approved list of RAM modules here but not sure if that has any effect... looks like it is a BIOS or Windows thing then.

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  • Interesting theory as this server has only 1 CPU installed. Not sure if it's a dual-CPU board though. Still waiting on feedback from the client.
    – Oliver Salzburg
    Jul 21, 2014 at 8:41
  • guess we will find out when your client replies :)
    – Sverre
    Jul 21, 2014 at 8:43
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    The board is a single-socket. Besides, if it was installed on the wrong side of a dual-socket board, the OS wouldn't even see it.
    – MSalters
    Jul 21, 2014 at 10:32
  • ok, I did not know the board is single-socket, and also I did not know how windows would react to RAM in the wrong place. (thanks)
    – Sverre
    Jul 21, 2014 at 10:34
  • I've run in to this with another Intel board. Since the motherboard only supports 2 GB of RAM per slot, that's all the OS will get to use. However, the RAM will still report that it is 4 GB when asked via SPI.
    – longneck
    Jul 23, 2014 at 15:33
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I agree with some of the answers listed already in particular with Mirrored Mode RAM.

Also, according to the official Intel site, your particular memory is not supported for the board chipset.

First thing I'd do is return the RAM back and get certified modules supported by the vendor.

Then check if it requires the memory to be matched on each side of the banks i.e. two modules in the correct slots per side. There could be every chance the BIOS is also out of date.

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