Nehalem Xeon performance on 32-bit OS, XP vs 2003

Question

I have to run 32-bit code on WinXP or Win2003. Nehalem Xeons (5500 series) should be the fastest, but I'm not sure what'll happen with the memory arrangement. I'm unsure about 2 parts:

1. To get a maximal speed memory setup, I'll need to install at least 6gb of RAM (to give each CPU 3 sticks to work with). Is the memory interleaved in such a way that a 32-bit OS (WinXP or 2003) will get maximum performance out of it? (I'm fine wasting a few gb of RAM).
2. Will Win2003's NUMA support work for the Xeon 5500s? (If so, I presume I should use Win2003 rather than WinXP?)

Answer 1

Yes, Server 2003 Enterprise is both NUMA-aware and have support for true 36-bit PAE addressing to address up to 64GB (in SP1 and later). So that is the best thing to use.

Answer 2

You seem to be confusing quantity of ram with speed of ram.

Usually you want to go with less quantity of ram that is higher quality rather than quantity of ram ( assuming you have enough ram total ).

More importantly... How are you using 4GB of RAM?!

If all the apps you are running need more than 4 GB total you might want to reconsider your approach... but then again to get to that much memory usage means you have already burned a lot of time...

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Slightly unrelated, regarding Windows XP 32 bit and ram limitations:

Windows XP 32 bit is limited to 4GB ( presumably because it ignores the 4 additional address bits that all new computers come with see Physical-address-extension ).

Answer 3

Why limit your system with a 32-bit OS? You can run 32-bit code just fine on a 64-bit OS, and 64-bit Server 2003 will run awesomely well on such a system as you describe. Personally I would go with 2008 or Linux.

Anyway, there is no conceivable reason to run 32-bit OS on a dual Nehalem Xeon. So get a 64-bit OS and 12 GB of RAM.