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  1. #1
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    Memory spec CL-11 What does it mean?

    I just ordered 4GB DDR3 PC3-12800 Unbuffered Non-ECC 1.34V CT5048807 CL=11
    --- What does the CL=11 mean and is it significant?

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    Super Moderator satrow's Avatar
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    CL 11 is a measure of the latency, CL 9 is lower = faster. Many other factors with the sub-timings of memory also contribute to how fast a certain stick/pair will perform in benchmarks. Real world differences aren't as marked as the difference between 11 and 9 might have you think - in many cases, there will be no noticeable difference outside of benchmarks.

    Here's a benchmark session with a number of DDR3 speeds.

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    Are you ordering 2x2GB or a single 4GB stick and are you adding either to any existing sticks ?

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    Super Moderator satrow's Avatar
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    It appears to be a single 4GB stick, the CT# indicates that it's specifically for a HP/Compaq ProBook 6560b.

    The other compatible options for the 6560b span the CL range 9-13, 1600/1866MHZ.

    If non-identical/matching RAM sticks are used, the speed will be reduced to that of the slowest stick for compatibility reasons - what is currently fitted?

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    Mis-matching can also cause black screening in running.

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    The installed memory in the computer has a Samsung 4GB 2Rx8 PC3-12800S-11-11-F3
    The one I ordered from Crucial is a 4GB chip and will be added
    I understand the concern about knowing what is currently fitted and that's why I had checked the installed chip before I ordered.
    In addition I checked some other memory websites and noticed there are different configurations than the 12800 and a few other items but I believe I made the right choice when I ordered the one I did as I am aware of mis-matching issues and Crucial hasn't been wrong yet in my experience
    I really appreciate all of your comments and information because it helps me learn something new and/or stay on top of what I'm doing

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    While Crucial's system scan will give compatible sticks, the free version of Speccy will give the manufacturer and Pt. No.

    When I upgraded this laptop for the second time (4GB - 8GB) the company I got my 4GB stick from sent me the wrong one which caused black screening, so I Googled for Samsung sticks and attached that URL to an email, pointing out the exact model I required.

    While Crucial will supply the same specs, I don't know if they will supply the same brand and mixing brands can also sometimes have adverse effects.

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    Super Moderator satrow's Avatar
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    The majority, if not all, of Crucial memory is made by Micron, the parent company, no strangers to using Samsung chips.

    WMI batch script #24 will output the memory stick's details.

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    The new 4GB memory chip is added in and the computer runs fine

    I checked the system information and this is the info
    Accessories > System tools > System information
    --- Installed Physical Memory (RAM) 4.00 GB > 8.00 GB
    --- Total Physical Memory 3.95 GB > 7.95 GB
    --- Available Physical Memory 2.73 GB > 5.67 GB
    What does the Available Physical Memory mean?
    --- Task manager shows 1.35 GB in use

  13. #10
    jwoods
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    It means the amount of RAM not currently in use by the system.

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    One thing that might be helpful to know. Windows is a modern operating system with paging and caching support. RAM is almost never "wasted" or inactive in such a system.

    Specifically with regards to the Available Physical Memory metric. Microsoft chose to represent the memory this way to emphasize the availability of this memory to run programs or other essential OS purposes. However it is unlikely to be unused memory, even while available.

    In reality the OS maintains a large disk cache to improve performance of the hard drive. This use of memory is dynamically reduced as more programs load, since supporting the programs load images is an essential feature while the disk cache is optional.

    In the end, the OS keeps track of all the memory capabilities of the computer. There's a hierarchy of storage, with respect to speed, capacity and persistence. Windows is aware of this hierarchy and makes use of the various memory types with this in mind.

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