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Kalman Rubinson
Guest
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 Posted:
Sun Nov 13, 2005 9:52 pm Post subject:
Value of dual-channel data transfer? |
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The manual for my new Fujitsu S7020D says that "dual-channel data
transfer is enabled automatically only when using two DDR2 533 memory
modules of the same capacity together."
Since they do not state what advantage this gains, can someone comment
on that? Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
Kal |
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Peter T. Breuer
Guest
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| Posted:
Sun Nov 13, 2005 10:05 pm Post subject:
Re: Value of dual-channel data transfer? |
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Kalman Rubinson <kr4@nyu.edu> wrote:
| Quote: | Since they do not state what advantage this gains, can someone comment
on that?
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It's the obvious advantage over single-channel data transfer!
Try travelling on a road with one lane, and on a road with two lanes. You
are a datum.
| Quote: | Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
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One would have more memory. One wuld have less. One would have faster
accesses. One would have slower (for spread data).
Peter |
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Barry Watzman
Guest
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| Posted:
Sun Nov 13, 2005 11:32 pm Post subject:
Re: Value of dual-channel data transfer? |
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It doubles the effective memory transfer rate. This can provide a
significant performance gain in some programs (at other times, the
advantage may not even be perceivable). In some rare case, with
programs and software applications that are highly memory intensive and
memory bound, this could nearly double performanced (but only very
localized performance of very memory intensive applications).
It's not enough to say that you need two modules of the same size.
Closer to correct would be that you need two IDENTICAL modules. In
fact, neither statement is absolutely correct. Modules of the same size
will not always enable dual channel support, however SOME non-identical
pairs of modules will support dual channel operation. But for most
people, the "identical" rule will work best, since evaluating
non-identical modules to determine if they will work in a dual channel
mode is beyond the ability of almost all users.
Kalman Rubinson wrote:
| Quote: | The manual for my new Fujitsu S7020D says that "dual-channel data
transfer is enabled automatically only when using two DDR2 533 memory
modules of the same capacity together."
Since they do not state what advantage this gains, can someone comment
on that? Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
Kal
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Barry Watzman
Guest
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| Posted:
Sun Nov 13, 2005 11:35 pm Post subject:
Re: Value of dual-channel data transfer? |
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Missed the last part of your post.
In some applications, more memory will provide a greater benefit than
faster memory, while in other applications, faster memory will provide a
greater benefit than more memory. It depends on what you are doing and
how the software that does it was written. It also depends on what
combination of applications happen to be running at once.
Kalman Rubinson wrote:
| Quote: | The manual for my new Fujitsu S7020D says that "dual-channel data
transfer is enabled automatically only when using two DDR2 533 memory
modules of the same capacity together."
Since they do not state what advantage this gains, can someone comment
on that? Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
Kal
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Kalman Rubinson
Guest
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| Posted:
Mon Nov 14, 2005 7:00 am Post subject:
Re: Value of dual-channel data transfer? |
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On Sun, 13 Nov 2005 17:05:49 +0100, "Peter T. Breuer"
<ptb@oboe.it.uc3m.es> wrote:
| Quote: | Kalman Rubinson <kr4@nyu.edu> wrote:
Since they do not state what advantage this gains, can someone comment
on that?
It's the obvious advantage over single-channel data transfer!
Try travelling on a road with one lane, and on a road with two lanes. You
are a datum.
|
OK. Got that.
| Quote: | Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
One would have more memory. One wuld have less. One would have faster
accesses. One would have slower (for spread data).
|
So, while I fully understand that statement, how do I use the
information to make a choice? If the answer is that it is application
dependant, it becomes a crap-shoot for me.
Kal |
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Kalman Rubinson
Guest
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| Posted:
Mon Nov 14, 2005 7:02 am Post subject:
Re: Value of dual-channel data transfer? |
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On Sun, 13 Nov 2005 17:35:00 GMT, Barry Watzman
<WatzmanNOSPAM@neo.rr.com> wrote:
| Quote: | Missed the last part of your post.
In some applications, more memory will provide a greater benefit than
faster memory, while in other applications, faster memory will provide a
greater benefit than more memory. It depends on what you are doing and
how the software that does it was written. It also depends on what
combination of applications happen to be running at once.
|
Thank you. Unfortunately, that leaves me unable to make a choice
without doing both and assessing the relative advantages across the
programs I will use. These are relatively uncommon applications
including ETF, RoomEQ Wizard, TEF and EZTune. I doubt most will
recognize them but they are common acoustic analysis programs.
Kal |
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Peter T. Breuer
Guest
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| Posted:
Mon Nov 14, 2005 8:27 am Post subject:
Re: Value of dual-channel data transfer? |
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Kalman Rubinson <kr4@nyu.edu> wrote:
| Quote: | On Sun, 13 Nov 2005 17:05:49 +0100, "Peter T. Breuer" <ptb@oboe.it.uc3m.es> wrote:
Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
One would have more memory. One would have less. One would have faster
accesses. One would have slower (for spread data).
So, while I fully understand that statement, how do I use the
information to make a choice?
|
You decide which scenario your applications (or the ones you care about)
would benefit from most. I seriously doubt that any of them are memory
bandwidth limited unless you are pre-rendering movie animations in real
time! But maybe they are! Check!
| Quote: | If the answer is that it is application
dependant, it becomes a crap-shoot for me.
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But everything is application dependent. If your application is "parking
the car", then maximum speed is unimportant to you and manoeuverability
is very important.
Peter |
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Barry Watzman
Guest
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| Posted:
Mon Nov 14, 2005 8:27 am Post subject:
Re: Value of dual-channel data transfer? |
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Very general rule of thumb, if you already have at least 512 megs of
memory, you will get more from dual channel than you will from more
memory (and yes, there are exceptions to this). In large part this is
because for most applications, expanding memory produces no major
benefit (again, there are exceptions). The Microsoft minimum for
Windows XP is 64 megs, it becomes "fully functional" at 128 megs, and no
one in their right mind would build a system with less than 256 megs.
But, by the same token, for most typical "office" applications, more
than 512 megs doesn't buy you very much (exceptions include gaming and
CAD, as well as some others). So if you have two 256 meg modules and
are considering replacing one of them with a 512 meg module, my advice
would be to wait until you can replace both of them with a 512 meg module.
Kalman Rubinson wrote:
| Quote: | On Sun, 13 Nov 2005 17:05:49 +0100, "Peter T. Breuer"
ptb@oboe.it.uc3m.es> wrote:
Kalman Rubinson <kr4@nyu.edu> wrote:
Since they do not state what advantage this gains, can someone comment
on that?
It's the obvious advantage over single-channel data transfer!
Try travelling on a road with one lane, and on a road with two lanes. You
are a datum.
OK. Got that.
Also, and for example, what would be the relative
performance of a 256/256 configuration (with dual-channel data
transfer) compared to a 256/512+ configuration (without)?
One would have more memory. One wuld have less. One would have faster
accesses. One would have slower (for spread data).
So, while I fully understand that statement, how do I use the
information to make a choice? If the answer is that it is application
dependant, it becomes a crap-shoot for me.
Kal
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