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Alex Andronov
Asked: 2009-05-20 22:50:36 +0800 CST

Is it better to have more small ram chips or fewer large ones?

  • 772

I am currently building a new server. I have options between say

32GB Memory for 2 CPUs, DDR3, 1066MHz (8x4GB Dual Ranked RDIMMs)

and

36GB Memory for 2 CPUs, DDR3, 1066MHz (18x2GB Dual Ranked RDIMMs)

Both at the same price.

Should I go for the higher ram amount or the fewer chips?

This will be for a Dell PowerEdge R710 with two Intel® Xeon® E5530, 2.4Ghz, 8MB Cache, 5.86 GT/s QPI, Turbo, HT

Thanks

memory xeon

5 Answers

  1. Best Answer

    Thanks for the update Alex. Most new 'Nehalem'-based servers such as the model you're looking at use triple-channel RAM, notice how they have 'divisible-by-three' memory slots (3, 6, 9, 12, 18 etc) where previous models had 'devisible-by-two' versions (2, 4, 8, 16 etc). You can put less than three modules in at a time but you're likely to miss out on the full performance of the new 'QPI'-based memory architecture.

    Also of great importance with these new chips is to balance your memory across processors - if you only have a single processor then you shouldn't put memory in the slots associated with the empty processor slot, only with the first processor - this effectively halves the memory capability of single-processor servers. If you have two processors you need to ENSURE that they both have the same amount AND type/size of memory as each other.

    Now onto your actual question. With these new servers the more physical memory chips you use the slower they get - they're still faster than the previous generation of chips/memory even at their slowest but you should aim to use less of the most capacious modules that make sense to you financially.

    Looking at the specific machine you want I would urge you to go with either 48GB Memory (12x4GB) or 24GB Memory (6x4GB) based on your requirements. Best of luck.

    • 19

  2. I would go for fewer chips, the reasoning being:

    1. This may leave some slots available for more RAM at a later date if necessary.
    2. When you decommission the server 3+ years from now, the 4 GB chips are more likely to be useful for salvaging than the 2 GB ones.

    I doubt having lots of chips would give you any noticeable performance improvements in most scenarios.

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  3. Higher density has nothing but benefits

    • Upgrade easily
    • More reliable
    • less power used (those few Watts tend to accumulate...)
    • 1

  4. The impact of triple vs. dual channel will not be so outspoken. However, within a triplet, your memory should be matched, so starting with 8 dimms now and expanding later might be more challenging unless you would be prepared to lose 2 dimms at that time. Do you need the memory right now? Then take the 18x2GB. Is it a luxury for now, and you are comfortable with upgrading later, go with 9x4GB if you can.

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  5. The short, easy answer to this is neither. Yet, with fewer chips, your data pulse takes less time to run-through the ram stick than if you had twice as many of those little buggars. This is, of course, a bit of a hairbrained answer, but in casual surfing and personal computing, the speed at which your signals run-through your ram is always best when it is faster (less chips, typically but NOT NECESSARILY). This is a great one for you Devil's Advocates out there! You can look at the chips as "resistors" of sorts, if ya' really need it to be a simple "picture" in your mind.

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