How To Tell if a Laptop RAM is Compatible and How to Use them ?
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Thread: How To Tell if a Laptop RAM is Compatible and How to Use them ?

  1. #1
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    How To Tell if a Laptop RAM is Compatible and How to Use them ?

    I hope this is the correct place to post this thread. If not, I trust it will be moved to a more appropriate place ?

    I am hoping to get some guide and clarifications on how to tell if a laptop RAM is suitable/compatible for a laptop. For example, I have laptop A that is installed with a RAM of
    512MB DDR PC2100 266MHz 200-pin SODIMM

    I also have another laptop B that is no longer working, but has a working RAM of
    512MB DDR PC2700 333MHz 200-pin SODIMM

    Can the RAM from laptop B be used for laptop A ?

    By just looking at the specifications of these 2 RAM, which factors should I look out for to determine if these two RAM are suitable and/or interchangeable between these 2 laptops - assuming both are laptops are working ?

    To start with, I know that for both laptops,
    a) the number of pins must be the same
    b) the type, ie SODIMM must both be SODIMM
    c) both must be the same DDR or DDR2 or DDR3, etc

    But I am not sure if
    i) the PC numbers (what does this stand for ?) must be the same
    ii) the MHz numbers (I understand this signifies the speed) should be the same and
    iii) are any other factors that I should be looking out for before using a RAM ?

    Finally, about using these RAM, if a laptop specs says the Max RAM the laptop can take is say, 2GB and has 2 slots,
    1) can a 2GB RAM be used in one slot only or must they be split up equally into 2 slots AND
    2) does it need to be of EQUAL rating on each slot - ie 1 GB on each of the slots or
    3) can 1 slot be used for !GB and he other for 512MB if the total 2GB is not required ?

    Any help and clarifications would be greatly welcome and appreciated. Many thanks in advance.
    Last edited by slickcondo; September 25th, 2017 at 07:47 PM.

  2. #2
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    i and ii)This article is a little old, but it gives you the gist.
    https://www.bleepingcomputer.com/tut...upgrading-ram/
    The PC# is related to the MHz. PC2700 = 333MHz.
    Clockspeed x Buswidth = Transfer rate
    333 x 8 = 2667 (rounded up to 2700)

    Usually, you can use PC2700 instead PC2100. It would just run at a slower speed.

    1 and 2) If the max is 2GB and there are 2 slots, that generally means 1GB per slot. It depends on the motherboard chipset and the density of the RAM chips. Even if you tried to put a 2GB stick into the slot, the chipset may only see 1GB. You should look up the make/model of the laptop.

    3) I'm guessing you mean running a 1GB and a 512MB stick. Again, it depends on the chipset. If it's a dual channel chipset, then running different sized sticks will degrade performance a bit. Overall, it would probably be better to have the extra RAM though.

    You can look up compatible RAM here: http://www.crucial.com/

  3. #3
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    Quote Originally Posted by Midknyte View Post
    i and ii)This article is a little old, but it gives you the gist.
    https://www.bleepingcomputer.com/tut...upgrading-ram/
    The PC# is related to the MHz. PC2700 = 333MHz.
    Clockspeed x Buswidth = Transfer rate
    333 x 8 = 2667 (rounded up to 2700)

    Usually, you can use PC2700 instead PC2100. It would just run at a slower speed.

    1 and 2) If the max is 2GB and there are 2 slots, that generally means 1GB per slot. It depends on the motherboard chipset and the density of the RAM chips. Even if you tried to put a 2GB stick into the slot, the chipset may only see 1GB. You should look up the make/model of the laptop.

    3) I'm guessing you mean running a 1GB and a 512MB stick. Again, it depends on the chipset. If it's a dual channel chipset, then running different sized sticks will degrade performance a bit. Overall, it would probably be better to have the extra RAM though.

    You can look up compatible RAM here: http://www.crucial.com/
    Thanks for the clarifications. I am aware of the compatible link you gave and also the one from Mr Memory website. I was trying to go without having to use these tools to know what are the factors to look out for as a minimum requirement.
    You are correct about point 3). Sorry I was did not make that clearer.

    Based on what you have said, does this mean that on my post, (a) to (c) are the main factors I need to be sure they are there ?
    And what if the PC numbers for the 2 RAMs are far apart ? Would they still work or they must be fairly similar to each other ? I suppose if they are too far apart, their speed would be affected but no harm to the laptop ?
    Thanks for letting me know the calculation to their equivalent on the 2 RAM I stated. Always something new to learn

  4. #4
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    Just for your information.

    Check you laptop information at crucial real close.
    Dell said 2 of my laptops had 4 GB limits, Crucial said 8 GB.
    Both have 8GB and run just fine.

    Mixing ram like that may
    1. Will not boot
    2. May boot but have all kinds of weird errors
    3. Work like we want it to.
    SMILE
    and post back. Let us know if it worked.
    [ Book mark this post to find it again]

    AntiX-16, MX-16 and Win 10

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    Quote Originally Posted by Train View Post
    Just for your information.

    Check you laptop information at crucial real close.
    Dell said 2 of my laptops had 4 GB limits, Crucial said 8 GB.
    Both have 8GB and run just fine.

    Mixing ram like that may
    1. Will not boot
    2. May boot but have all kinds of weird errors
    3. Work like we want it to.
    Thanks Train. I was just reading the BleepingComputer article suggested by Midknyt and was already thinking it's more complicated than just the factors I have stated on my post earlier. Your reply just confirmed that there is no hard and fast rule and even the fact that a simple task of mixing RAM is not as straight forward as it seems
    Thanks for the tip on using the crucial site. But I have found the Mr Memory site is a lot easier and clearer to use and read the result.

  6. #6
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    I was trying to go without having to use these tools to know what are the factors to look out for as a minimum requirement.
    All you posted were the RAM specs, so it's hard to say for sure. I can only give you an educated guess.

    #of pins and RAM type definitely need to match. You might also need to know the density of the RAM chips. As I mentioned, a 2GB stick may only be recognized as 1GB (I.E. the RAM density is higher than the chipset can read)
    You still didn't post any specific info about the RAM sticks or the laptops.

    And what if the PC numbers for the 2 RAMs are far apart ?
    I'm assuming you mean if you had 2 sticks. The slowest RAM would be the limiting factor.
    I.E. If you have a PC2700 stick and a PC2100 stick, both would run at PC2100 levels.

    As Train mentioned, there can be problems that arise when you mix RAM.

  7. #7
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    Example Mr Memory says 4 GB for my Dell D630 and Crucial says 8 GB which I have installed.
    https://www.mrmemory.co.uk/memory-ra.../latitude/d630
    http://www.crucial.com/usa/en/compat.../latitude-d630
    SMILE
    and post back. Let us know if it worked.
    [ Book mark this post to find it again]

    AntiX-16, MX-16 and Win 10

  8. #8
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    Quote Originally Posted by Midknyte View Post
    All you posted were the RAM specs, so it's hard to say for sure. I can only give you an educated guess.

    #of pins and RAM type definitely need to match. You might also need to know the density of the RAM chips. As I mentioned, a 2GB stick may only be recognized as 1GB (I.E. the RAM density is higher than the chipset can read)
    You still didn't post any specific info about the RAM sticks or the laptops.


    I'm assuming you mean if you had 2 sticks. The slowest RAM would be the limiting factor.
    I.E. If you have a PC2700 stick and a PC2100 stick, both would run at PC2100 levels.

    As Train mentioned, there can be problems that arise when you mix RAM.
    Thanks for your clarifcations. The info you stated is all that I wanted to know. I am aware that if a laptop can only take a max of say 2GB RAM, and have 2 slots, then I should not exceed this Max when the total of the 2 slots are used.

  9. #9
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    Quote Originally Posted by Train View Post
    Example Mr Memory says 4 GB for my Dell D630 and Crucial says 8 GB which I have installed.
    https://www.mrmemory.co.uk/memory-ra.../latitude/d630
    http://www.crucial.com/usa/en/compat.../latitude-d630
    So it's a good point to check on more than one sites to see if their info is the same....thanks for this point.
    I guess it's a risk if you install the rating over what is the Max in that it may blow the RAM chip or some parts of the laptop or just that is may not work properly ? Most important is to avoid blowing something in the laptop.

  10. #10
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    Just pay good money for something that does not work correctly is about all.

    Remember with 32-bit OSs, you are limited to 4 GB of ram.
    SMILE
    and post back. Let us know if it worked.
    [ Book mark this post to find it again]

    AntiX-16, MX-16 and Win 10

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