Dual Channel Memory question

Discussion in 'Computers' started by MarkHastings, Mar 27, 2006.

  1. MarkHastings

    MarkHastings Executive Producer

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    I'm purchasing a Dell laptop and I'm going for the 1GB of memory. It was suggested (obviously) to see if the 1GB is a single chip because that leaves the other slot open for extra memory (down the road).

    FYI, I'm getting a Dell Inspiron E1705, which does have 2 memory slots. I'm getting this installed in the system: 1GB Shared Dual Channel DDR2 SDRAM at 667MHz

    Now I'm not sure if it's one 1GB chip or two 512MB chips. As I did some research, I found this on Dell's site:Now it sounds like having two 512MB chips may perform better than one 1GB chip? Is this true? I assume it has to do with the fact that they are 'dual channel'?

    If the above is true, while both slots would be taken, I may have better memory performance, so as long as I don't really plan on upgrading memory, I shouldn't be concerned if there are two 512's?

    Can anyone make sense of my ramblings? [​IMG]

    Obviously having two 512's means that they'd both need to be replaced if I ever wanted more memory, but I really don't see that happening as I use my desktop as my 'workhorse' - the laptop is just for 'fun' stuff.
     
  2. Max Leung

    Max Leung Producer

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    Dual channel should give you more performance. Theoretically 2x the memory bandwidth, although in the real world that may not account for more than 10-20% speed boost...it really depends on the application.
     
  3. Mike_J_Potter

    Mike_J_Potter Second Unit

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    Yes you do have dual channel ram. You will get some increase in performance though it won't be to drastic. Here is a site that compares dual channel to single including benchmarks, they test a AMD DDR system not a intel ddr2 system like yours but the difference will be almost the same.

    http://www.tcmagazine.info/articles....ge=1&pagenum=2
     
  4. MarkHastings

    MarkHastings Executive Producer

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    Thanks guys, but can you tell me if there is a difference (in speed) between installing one 1GB chip and two 512MB chips?
     
  5. Rommel_L

    Rommel_L Second Unit

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    Mark,

    1GB in dual channel mode means TWO 1GB sticks running in dual channel mode. Max already stated the so called real world advantage, but unless you use this as a gaming machine, it would make more sense running it in single channel with 2GB of total physical RAM for everyday applications...
     
  6. Kimmo Jaskari

    Kimmo Jaskari Screenwriter

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    Actually, that's quite wrong.

    Dual channel mode means just that there are two memory chips in use, and that they can transfer data in parallell to improve memory speeds and thus the speed of the computer.

    1 GB dual channel is two 512MB sticks, running in parallell to speed up memory access.

    If you have two 1 GB sticks in the machine, you get 2 GB total memory space.

    Either way, dual sticks on a dual channel capable computer will give a speed advantage over a single but larger stick of RAM, because the bandwidth between memory and CPU will double (or at least increase noticeably... not sure it's actually double speed.) Most high-performing computers these days want two sticks of RAM and the memory manufacturers are even selling memory in dual-stick kits at a slightly reduced price compared to buying two sticks separately.
     
  7. MarkHastings

    MarkHastings Executive Producer

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    Thanks Kimmo, that was the answer I was looking for. Actually, the laptop was only configurable with dual channel memory, so I really don't have a choice either way. I just wanted to be certain as to what was being installed. Even though I'd have to replace both chips if I ever wanted to upgrade (in the future), it sounds like dual channel is the better way to go.

    [​IMG]
     
  8. Scott L

    Scott L Producer

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    So if you have (3) 512mb sticks it will be slower than just two of them?
     
  9. Kimmo Jaskari

    Kimmo Jaskari Screenwriter

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    Lots of fun stuff on Wikipedia... try this: http://en.wikipedia.org/wiki/Dual-channel

    Three chips will almost assuredly (I admit I'm not 100% sure) disable the dual channel mode and fall back to using single channel mode to access all memory. That will definitely slow down access between the memory and the CPU. For motherboards and systems that support dual channel mode, the ideal is two matching chips.
     

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