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Thread: Which memory is faster?

  1. #1
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    Which memory is faster?

    I have an old dual v2 xeon. I bought it as a referb, and came with 8x8gb. I happened to have four 16gb DIMMs that I think are compatible. So I swapped those out with 4x16gb, hoping it would be faster. But I am not really sure how fast this old machine can run memory, regardless of the speed of the DIMMs. Here is what CPU-Z tells me. Is it possible to tell by this info, which is faster? I am having trouble telling because one has a higher frequency, but the other has lower latency. Of course, I could be reading this all wrong.

    8x8gb:


    4x16gb:
    “Good intentions will always be pleaded for every assumption of authority. It is hardly too strong to say that the Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern well, but they mean to govern. They promise to be good masters, but they mean to be masters.” ~ Daniel Webster

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    Re: Which memory is faster?

    The 8x8 will be much faster because that allowed each Xeon to have 4 modules. When you switched to 4x16, each Xeon only had 2 modules which cut bandwidth in half.


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    Re: Which memory is faster?

    Well dang. I thought I was starting to understand memory, but I guess not. I thought that 4xN is faster than 8x(N*.5)?
    “Good intentions will always be pleaded for every assumption of authority. It is hardly too strong to say that the Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern well, but they mean to govern. They promise to be good masters, but they mean to be masters.” ~ Daniel Webster

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  4. #4
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    Re: Which memory is faster?

    Quote Originally Posted by zombie67 View Post
    Well dang. I thought I was starting to understand memory, but I guess not. I thought that 4xN is faster than 8x(N*.5)?
    4x is faster per cpu than 8x. But it's per cpu.

    For mainstream cpus, 2x is faster.


  5. #5
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    Re: Which memory is faster?

    Ah. Per CPU. I thought 4 channels meant 4 DIMMs. But the rule is "one DIMM channel, per CPU"? So in this case, the CPU has 4 channels x 2 CPUs = 8 DIMMs?

    Any chance I could have known your answer from the numbers in the images I posted? What would have told me what you summarized? Or was the info from CPU-Z not sufficient to make a decision?
    “Good intentions will always be pleaded for every assumption of authority. It is hardly too strong to say that the Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern well, but they mean to govern. They promise to be good masters, but they mean to be masters.” ~ Daniel Webster

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  6. #6
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    Re: Which memory is faster?

    Quote Originally Posted by zombie67 View Post
    Ah. Per CPU. I thought 4 channels meant 4 DIMMs. But the rule is "one DIMM channel, per CPU"? So in this case, the CPU has 4 channels x 2 CPUs = 8 DIMMs?

    Any chance I could have known your answer from the numbers in the images I posted? What would have told me what you summarized? Or was the info from CPU-Z not sufficient to make a decision?
    Yes, 4 channels x 2 CPUs = 8 DIMMs is the right way to look at it.

    CPU-Z shows in the upper righthand corner the "Channel #". With 8x8 it says quad and with 4x16 it says dual.


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