I have 64 bit machine with 1 CPU only. From what is remember, that means my physical RAM is expandable to 2^64 bytes as that is what is addressable memory. 1. Is this correct?

Now, i intend to have Windows Server 2008 R2 STANDARD edition installed on it and MS says that max physical allowed = 32 GB http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx

My intention is to use this machine as a web server using IIS7

  1. The question that i have here is :- If i put 32 GB with only 1 CPU on this machine, is it capable of fully utilizing the same or are there some constraints with having only 1 CPU?
  • With a Nelahem (Xeon 55xx) you have a NUMA architecture, so you can only put memory on the slots attached to that CPU (see my answer below). However, any modern Nelahem box will take well over 32GB per CPU socket. Jun 30, 2010 at 11:27
  • @Concerned - Thanks that really helps! With respect to your comment about a modern Nehelam box - Sorry for being obtuse but are you referring to the motherboard and if so how can i check if the one i am looking at will support it or not?
    – Jagmag
    Jun 30, 2010 at 11:33
  • Xeon 5500 series use the 'Nelahem' micro-archiecture, which replaces the front-side bus memory architecture of older Xeon models. This is a NUMA architecture similar to AMD's Hypertransport bus used on the Opteron, so memory channels are tied to specific CPU sockets. Anything with a 5500 or later series Xeon is a 'Nelahem' based chip. Jun 30, 2010 at 11:56

2 Answers 2


Depends on the architecture. Some, such as Nelahem or Opteron have NUMA architectures where the memory is tied to a physical CPU. In this case, with only one socket filled you can only populate the memory slots attached to that CPU.

Otherwise, you can add as much memory as the machine can physically support.

The 32GB limit on Windows Server SE is arbitrary, but it can only use 32GB for a single system image. You can run multiple instances under a hypervisor, and potentially have more than one instance of SE with 32GB if the hypervisor and hardware will allow it.


Windows won't have any problem so long as it's a 64-bit application but obviously you've not listed your hardware, that's would be my only worry - if you let us know what it is we can look into that.

  • Hardware is not finalized but i am potentially looking at Intel(R) Quad Core E5506 Xeon(R) CPU, 2.13GHz, 4M Cache, 4.86 GT/s QPI as the CPU - most likely on a Dell PowerEdge T410 / PowerEdgeR510 Rack depending on whether the client goes with either tower / rack Ram would be the 16GB Memory (8x2GB), 1333MHz, Dual Ranked RDIMMs. Does that help?
    – Jagmag
    Jun 30, 2010 at 11:23
  • I'd assumed you'd be putting in 32GB given the question - I'd go for an E5520 or E5620 if I were you, the E5506 doesn't provide hyperthreading, the extra money for the 55/5620 is well worth it.
    – Chopper3
    Jun 30, 2010 at 11:51
  • Intending to start with 16 gb but wanted to make sure that inspite of 1 CPU, based on usage, that i did have the option of going up to 32GB if needed. Thanks for the comment about using the 5520 / 5620. That really helps!!
    – Jagmag
    Jun 30, 2010 at 12:05

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