Adding Non DualChannel Ram to a machine running in Dual Channel Mode

Discussion in 'PC hardware help' started by ima49311, Feb 7, 2006.

  1. ima49311

    ima49311 Regular member

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    Is this a VERY bad idea? what would happen? I have some ram laying around that (speedwise) work in my computer at work. I want to up the ram on the machine, but currently its using dual channel ram.. the memory i would be adding is not dual channel. Thanks for the help.
     
  2. ddp

    ddp Moderator Staff Member

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    the computer will run in regular mode & not in dual channel which is supposedly faster.
     
  3. Distorded

    Distorded Regular member

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    I like the "supposedly" factor.
     
  4. ozzy214

    ozzy214 Regular member

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    From what I was reading the other day it will still run in dual channel as long as yeah have pairs. So have yeah dual channel pair and then a mismatched pair as long as it is the same speed. Some people actually think this is hype so the ram companies can make more money selling dual channel kits. personally I have one set of dual channel and two identical modules that are rated on the box for non dual channel. These both run on my epox board without no instability plus the board and cpuid reports everything is running in dual mode and that the speed is correct. So im leaning towards the part that is hype and as long as you have two of the same make, speed, and density then it will work just fine. To each their own.:>
     
  5. The_OGS

    The_OGS Active member

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    True of course! Dual-channel kits are simply 2 sticks packaged together, LoL ;^)
    The specific issue is memory access bandwidth. 1 stick of, say, PC3200DDR is accessed by 64-bit data path. This compares poorly with video boards, for example, where the lowest-performing have 128-bit memory and high-performance boards have 256-bit memory.
    So running in dual-channel mode will increase your memory access to 128-bit bandwidth, doubling the 400DDR spec from theoretical 3200MB/s to 6.4GB/s
    So it is important not to disrupt this setup unless a substantial increase in memory size would result, ie. going from 2 x 256MB to 1 x 1GB...
    You would just be waiting then, to get your hands on a second 1GB stick, to go back to 128-bit memory again :^)
    The problem is, it can be challenging to match 1 existing stick - so of course we try to purchase 2 (identical) at the same time.
    Note: 4 sticks in 128-bit memory mode will always be at a disadvantage to 2 sticks. Many mobos will support only PC2700 speeds w/ 4 sticks installed... and an extra 'tick' (timing delay) is always applied when multiple sticks are in place.
    Anyway 2 x 2700MB/s is still more than 3200MB/s bandwidth - so 4 sticks are better than 1, but not as good as 2!
    Hope this helps,
    Regards
     
  6. ima49311

    ima49311 Regular member

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    ok, i'll give it a shot then do a memory test to see if everything is good.. thanks for the help..
     

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