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Thread: 1 RAM stick better than two unequal ones?

  1. #1
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    Default 1 RAM stick better than two unequal ones?

    Recently, I upgraded my PC's RAM to 1.5 GB (Previously, it had been 512 MB). Before upgrading, there had been one stick of 512 MB RAM (not two 256 MB ones). So, I bought another RAM stick, a 1GB one. When I had installed this RAM stick alongside my old RAM, I booted up the computer.
    At boot-up, a black screen with a message appeared, saying:
    'The firmware has detected that the amount of memory in Channel A is unequal to the amount in Channel B. For maximum performance, make sure that the amount of memory in both channels in equal.
    Press Enter to continue.'
    I pressed Enter to boot up the OS. Anyway, the computer ran fine. It was noticeably faster than before, especially when multitasking. But the black message that I had seen on bootup still bugged me.
    I just wanted to know: was it a good idea to let a 512 MB RAM stick be installed alongside a 1 GB stick? Or, to make the question simple: would it be in any way better if I removed the 512 MB RAM stick and left myself with one chip of 1GB RAM instead of two different ones? Since with 1.5 GB RAM, hardly 30% of RAM is used when I'm normally working, 1 GB RAM wouldn't be so less that swap would have to be used; so I suppose performance would be more or less the same.
    (Sorry if this question contains non-hardware comments, I just couldn't find anywhere else to post it)

  2. #2
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    Exclamation Re: 1 RAM stick better than two unequal ones?

    Quote Originally Posted by BrownieCat View Post
    Recently, I upgraded my PC's RAM to 1.5 GB (Previously, it had been 512 MB). Before upgrading, there had been one stick of 512 MB RAM (not two 256 MB ones). So, I bought another RAM stick, a 1GB one. When I had installed this RAM stick alongside my old RAM, I booted up the computer.
    At boot-up, a black screen with a message appeared, saying:
    'The firmware has detected that the amount of memory in Channel A is unequal to the amount in Channel B. For maximum performance, make sure that the amount of memory in both channels in equal.
    Press Enter to continue.'
    I pressed Enter to boot up the OS. Anyway, the computer ran fine. It was noticeably faster than before, especially when multitasking. But the black message that I had seen on bootup still bugged me.
    I just wanted to know: was it a good idea to let a 512 MB RAM stick be installed alongside a 1 GB stick? Or, to make the question simple: would it be in any way better if I removed the 512 MB RAM stick and left myself with one chip of 1GB RAM instead of two different ones? Since with 1.5 GB RAM, hardly 30% of RAM is used when I'm normally working, 1 GB RAM wouldn't be so less that swap would have to be used; so I suppose performance would be more or less the same.
    (Sorry if this question contains non-hardware comments, I just couldn't find anywhere else to post it)
    What you are saying is quite common. Many motherboards exhibit strict rules about memory. Usually when 2 memories are used they must be identical size and speed and must also match the specs for the MBO. Some MBO's allow a single stick but this too must match with the specs required for the MBO. Combining different sizes is very bad as how can the system properly deside on the matched size of memory. Using different speeds can be disastrous as information from one bank will arrive at a different time than the other.

    When your up to your a** in Alligators it's pretty hard to remember you intended to drain the swamp (author unknown)

  3. #3
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    Default Re: 1 RAM stick better than two unequal ones?

    Quote Originally Posted by techwiz03 View Post
    What you are saying is quite common. Many motherboards exhibit strict rules about memory. Usually when 2 memories are used they must be identical size and speed and must also match the specs for the MBO. Some MBO's allow a single stick but this too must match with the specs required for the MBO. Combining different sizes is very bad as how can the system properly deside on the matched size of memory. Using different speeds can be disastrous as information from one bank will arrive at a different time than the other.

    Does that mean it would be better if I removed the 512MB stick? If my PC's performance won't suddenly reduce drastically if I do that, (which I expect it won't ) then that's not a good choice. But I guess 1GB is also good enough for me.

  4. #4
    Camalen NNTP User

    Default Re: 1 RAM stick better than two unequal ones?

    BrownieCat wrote:

    > At boot-up, a black screen with a message appeared, saying:
    > 'The firmware has detected that the amount of memory in Channel A is
    > unequal to the amount in Channel B. For maximum performance, make sure
    > that the amount of memory in both channels in equal.
    > Press Enter to continue.'


    Is it a recent motherboard? Most surely you are facing a dual-channel
    configuration:

    http://en.wikipedia.org/wiki/Dual-channel_architecture

    "If the motherboard has two pairs of differently colored DIMM sockets (the
    colors indicate which bank they belong to, bank 0 or bank 1), then one can
    place a matched pair of memory modules in bank 0, but a different-capacity
    pair of modules in bank 1, as long as they are of the same speed. Using
    this scheme, a pair of 1 GB memory modules in bank 0 and a pair of matched
    512 MB modules in bank 1 would be acceptable for dual-channel operation."

    So unless you get some glitches (random system restarts or shutdowns) I will
    keep that 512 MB module on.

    Greetings,

    --
    Camalen

  5. #5
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    Default Re: 1 RAM stick better than two unequal ones?

    Some mobos require for single channel operation for you to put these modules on specific banks. F.ex my ASUS mobo requires modules to be put on Bank B (which has two channels so I can place two modules) for single-channel mode only. Since you mix a Gig module with a 512MB one, you'll be operating in single-channel only (double channel requires modules of identical sizes) so check the docs of your mobo where modules for single-channel only need to be placed

    Also, what techwiz03 said that using different speeds will be "disastrous" is a lie. Memory controllers will automatically detect the speeds of modules and if they are not the same, will automatically clock all modules to the speed of the slowest module. F.ex you can mix DDR333 with DDR400 but the controller will downclock the DDR400 to DDR333 speed (200 MHz -> 166 MHz). On the other side, and note I'm only talking here about older DDR1 memory, is that all DDR1 chips can operate at higher speeds, i.e. DDR333 and even DDR266 can operate just fine at 200MHz (DDR400) as there's absolutely no difference between a DDR266 chip and a DDR400 chip. The reason modules are sold with a DDR<speed> stickers on them is to tell at which speed that module is guaranteed to operate (ie, the factory has tested this module only at this speed and thus markets it only for this speed and can guarantee it'll operate correctly at it).

  6. #6
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    Default Re: 1 RAM stick better than two unequal ones?

    Oops... I removed the 512 MB RAM stick before I read the new posts...
    Anyway, I'm not noticing any difference between the performance of my PC with 1 GB RAM and with 1.5 GB RAM. Right now, as I'm typing this in Firefox (the only application running), only 24 % of my total 1GB RAM is being used, and that's a pretty good sign. Since 1.5 GB RAM isn't going to give me any benefit as compared to 1GB, I'll stick with it. Besides, I don't really need so much RAM; I upgraded because I experienced slowdowns when I began multitasking on 512MB.
    Currently I'm happy with 1GB. My system's become really snappy as compared to before.

  7. #7
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    Default Re: 1 RAM stick better than two unequal ones?

    If your system is at some limit for ram usage or your motherboard is particularly picky then having identical modules can be helpful. Most people wouldn't notice any speed difference from using mismatched modules. Having enough ram is much more useful than having matched modules.

    All that said, most linux systems will run very well with 1GB of ram with not much improvement after that. I've noticed significant improvements with upgrades to 1GB of ram from 512mb or less.

    A 1GHz P3 with 1GB of ram will have no trouble with opensuse 11.1. The same system would choke on Vista.

  8. #8
    Will Honea NNTP User

    Default Re: 1 RAM stick better than two unequal ones?

    microchip8 wrote:

    > Some mobos require for single channel operation for you to put these
    > modules on specific banks. F.ex my ASUS mobo requires modules to be put
    > on Bank B (which has two channels so I can place two modules) for
    > single-channel mode only. Since you mix a Gig module with a 512MB one,
    > you'll be operating in single-channel only (double channel requires
    > modules of identical sizes) so check the docs of your mobo where modules
    > for single-channel only need to be placed


    Does it not follow that having a single module implies single channel
    operation in the initial configuration? That being the case, adding a
    second module that forces single channel operation is a wash - you gain
    performance via increased cache and reduced swapping - but you don't
    really "lose" anything by not using the dual channel, you just don't
    realize the potential gain hardware.

    --
    Will Honea

  9. #9

    Default Re: 1 RAM stick better than two unequal ones?

    if you are using single channel memory now then adding a second module to your system will increase it's performance, whether it is a different capacity or speed. I just pulled a pc 2100 128mb stick (one of two matched sticks that came with the machine) out of an old dell dimension 2400 this morning and added a pc3200 512mb stick in and its a huge difference. the pc3200 is down clocks to 266mhz, but it's still a 512mb increase in memory.

  10. #10
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    Default Re: 1 RAM stick better than two unequal ones?

    Quote Originally Posted by Will Honea View Post
    microchip8 wrote:

    > Some mobos require for single channel operation for you to put these
    > modules on specific banks. F.ex my ASUS mobo requires modules to be put
    > on Bank B (which has two channels so I can place two modules) for
    > single-channel mode only. Since you mix a Gig module with a 512MB one,
    > you'll be operating in single-channel only (double channel requires
    > modules of identical sizes) so check the docs of your mobo where modules
    > for single-channel only need to be placed


    Does it not follow that having a single module implies single channel
    operation in the initial configuration? That being the case, adding a
    second module that forces single channel operation is a wash - you gain
    performance via increased cache and reduced swapping - but you don't
    really "lose" anything by not using the dual channel, you just don't
    realize the potential gain hardware.

    --
    Will Honea
    No, it does not follow. This is a chipset limitation and is even mentioned in the manual. If you place a single module on Bank A and boot this mobo, it won't fire up as it'll think there's no memory installed. If you place that module in Bank B (either channel 1 or 2) it'll happily boot

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