4GB RAM issues

Discussion in 'Computer Components' started by zz101, May 5, 2007.

  1. zz101

    zz101
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    Having found some bargain RAM earlier I ordered 4 x 1GB sticks to replace my failing 4x512MB sticks - the extra 2GB not really needed yet though.

    However following some googling it seems...

    32bit XP SP2 cant use more than 3GB RAM

    Installing 4GB RAM on my board may actually be slower than 2GB RAM??

    You can use the spare 1GB RAM as a faster page file?

    Anyone shed any light in these?

    Will try and cancel the order but it may be too late. :thumbsdow
     
  2. bond007

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    32bit Win XP can allocate upto 4GB of address space. This means that if you put in 4GB of RAM, you will only see that full 4GB if nothing else in your PC needs address space too. This will not happen. Your graphics card needs address space, sound card, nic etc They all will be allocated address space, the remaining address space will then be assigned to your ram. The 3GB limit is that the last 1GB of address space is used for the driver address space (the graphics card etc) but it will give you what ever it has free. So you will be able to access more than 3GB of ram, if you dont use up 1GB of address space on all your drivers.

    You can get passed this by pushing your drivers address space out of the 4GB limit, by using the /PAE for your boot switch (in the boot.ini file) but this isnt generally recommended as it requires the drivers to support the addressing above 4GB.

    The performance shouldnt be slower, this would only happen if you were using (32bit) 2000 advanced server, or 2003 Enterprise and above, as that can address above 4GB of RAM using an additional paging layer for memory, which slows things down.

    The you can use the spare 1GB of RAM as a faster paging file, nope you cant, if you could, that would mean you could access the RAM in the first place, so why not just have it as RAM
     
  3. zz101

    zz101
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    Ah right thanks! :smashin:
     
  4. Paul Shirley

    Paul Shirley
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    Using 4 DIMMs on some mboard and/or CPUs can force them to run with a lower clock. My Athlon64 X2 will run 2 DIMMs at 400Mhz, 4 at 333Mhz. Check your mboard manual for confirmation. Meanwhile in the wacky world of RAM timings slower clocking doesn't necessarily mean lower performance!

    In real life you'll rarely see any difference worth worrying about with 4 sticks over 2, could be faster,slower or the same. Also worth noting most users won't see any improvement past 2Gb of RAM, turns out be be hard to use that much RAM - I've been running 2Gb without at swapfile for a year+ and it takes bugs in Firefox to chew up all the RAM.

    I wouldn't worry about the speed hit or not installing all the RAM if you do see a speed difference.
     

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