Can someone pls explain about dual channel memory on these points

1) In order to use Dual Channel memory (DDR2 in this),  the mobo has
to be DC capable - but does the memory also ? I ask becuase I see the
terms "single sided" and double sided" memory modules.  I understand
that some DC mobos can operate with either - but I mean in order to
use allow Dual Channel memory to work as Dual channel memory, does it
need doubel-sided memory modules?

2) Question by example here:
If I put 2 x 1Gb (double sided?) memory in dual channel mobo, will
that appear as just *One* Gb of (presumably faster) memory to the OS?
i.e. are we getting faster memory performance at the cost of having to
double the phyiscal memory to do it?

I can see I'm not clear how the "single/double sided" memory thing
fits with "dual channel".

Thanks for some clarity on any of this.

On Fri, 06 Nov 2009 11:21:23 +0000, dave wrote:

> Can someone pls explain about dual channel memory on these points
> 
> 1) In order to use Dual Channel memory (DDR2 in this),  the mobo has to
> be DC capable - but does the memory also ? I ask becuase I see the terms
> "single sided" and double sided" memory modules.  I understand that some
> DC mobos can operate with either - but I mean in order to use allow Dual
> Channel memory to work as Dual channel memory, does it need doubel-sided
> memory modules?

The terms single- and double-sided refer to the chip density. Literally, 
single-sided modules only have chips on one side of the PCB. They have no 
bearing on dual-channel mode.

As long as the memory is compatible with your MB, and the two modules are 
identical (or at least similar), it will work in dual channel mode.

> 2) Question by example here:
> If I put 2 x 1Gb (double sided?) memory in dual channel mobo, will that
> appear as just *One* Gb of (presumably faster) memory to the OS? i.e.
> are we getting faster memory performance at the cost of having to double
> the phyiscal memory to do it?

It would be pretty pointless if that was the case; the performance gains 
from dual channel memory operation are both small, and variable.

The MB will see all of the memory you plug in, provided it is compatible 
and within the slot and overall limits of the MB.
 
> I can see I'm not clear how the "single/double sided" memory thing fits
> with "dual channel".
> 
> Thanks for some clarity on any of this.

This any help?

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

Chris

-- 
Remove prejudice to reply.

On Fri, 06 Nov 2009 11:21:23 +0000, dave  wrote:
>Can someone pls explain about dual channel memory on these points
>
>1) In order to use Dual Channel memory (DDR2 in this),  the mobo has
>to be DC capable - but does the memory also ?

No, it's a motherboard thing.

> I ask becuase I see the
>terms "single sided" and double sided" memory modules. 

This is just talking about the physical arrangement of chips on the
module, and not anything to do with dual channel. Back in the old days
of SDRAM, "single sided" could be significant - half the number of
chips means that they are higher density (unsurprisingly), and some
mobos couldn't deal with the higher density. These days, DDR upwards,
it should be irrelevant.

> I understand
>that some DC mobos can operate with either - but I mean in order to
>use allow Dual Channel memory to work as Dual channel memory, does it
>need doubel-sided memory modules?

Nope.

>2) Question by example here:
>If I put 2 x 1Gb (double sided?) memory in dual channel mobo, will
>that appear as just *One* Gb of (presumably faster) memory to the OS?

Nope, two. 

Having two memory modules means that the mobo can do "dual channel"
mode. That means that the mobo can send twice as many memory access
requests, nothing more. It only gets you 1-3% extra speed of memory
access, so it's hardly even worth worrying about.

	Cheers - Jaimie
-- 
#include "clue.h"

On Fri, 06 Nov 2009 11:41:44 GMT, Chris Whelan
 wrote:


>> 2) Question by example here:
>> If I put 2 x 1Gb (double sided?) memory in dual channel mobo, will that
>> appear as just *One* Gb of (presumably faster) memory to the OS? i.e.
>> are we getting faster memory performance at the cost of having to double
>> the phyiscal memory to do it?
>
>It would be pretty pointless if that was the case; the performance gains 
>from dual channel memory operation are both small, and variable.

Well maybe there would be a point *if*, although no capacity increase,
it might appear as 1Gb of *much faster* memory. - as afai can see
getting reduced access times is now getting near physical limits (?). 
Anyway - is not the case.

On Fri, 06 Nov 2009 12:26:29 +0000, Jaimie Vandenbergh
 wrote:

>Having two memory modules means that the mobo can do "dual channel"
>mode. That means that the mobo can send twice as many memory access
>requests, nothing more. It only gets you 1-3% extra speed of memory
>access, so it's hardly even worth worrying about.
>
I see.  Yes the bit of reading I've done says up tp 15% - but then who
actual gets that :-)
One interesting line from that wiki link says that "more sig.
difference in apps. that manipulate large amounts of data in-memory."
If I get this pc built will be interesting to see.

The message 
from dave  contains these words:

> On Fri, 06 Nov 2009 12:26:29 +0000, Jaimie Vandenbergh
>  wrote:

> >Having two memory modules means that the mobo can do "dual channel"
> >mode. That means that the mobo can send twice as many memory access
> >requests, nothing more. It only gets you 1-3% extra speed of memory
> >access, so it's hardly even worth worrying about.
> >
> I see.  Yes the bit of reading I've done says up tp 15% - but then who
> actual gets that :-)

 I suppose those folk who are running dual or quad core cpus. The 1-3%
figure (usually more like 2-5%) applies to single core cpu systems.

> One interesting line from that wiki link says that "more sig.
> difference in apps. that manipulate large amounts of data in-memory."
> If I get this pc built will be interesting to see.

 However, if my experience with a SFF Mini-Q Jetway branded 'bare bones'
system is anything to go by, it can make a significant difference when
relying on  built in graphics that uses shared main system memory. In
fact so much so as to allow the frame rate benchmark figures in the
Unreal game to get very close to what you'd expect when using a seperate
plug in AGP MX440 card with its own independent memory (exactly the same
video chip that's used by the MoBo).

 Dual channel operation definitely seems to mitigate the deletorious
effects of trying to share system memory between the CPU and an on-board
GPU (but this may only apply when the IGP and MoBo chipset are both made
by the same manufacturer ;-).

HTH

-- 
Regards, John.

 Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

"Johnny B Good"  wrote in message 
news:31303030373730364AF44D1F63@plugzetnet.co.uk...
> The message 
> from dave  contains these words:
>
>> On Fri, 06 Nov 2009 12:26:29 +0000, Jaimie Vandenbergh
>>  wrote:
>
>> >Having two memory modules means that the mobo can do "dual channel"
>> >mode. That means that the mobo can send twice as many memory access
>> >requests, nothing more. It only gets you 1-3% extra speed of memory
>> >access, so it's hardly even worth worrying about.
>> >
>> I see.  Yes the bit of reading I've done says up tp 15% - but then who
>> actual gets that :-)
>
> I suppose those folk who are running dual or quad core cpus. The 1-3%
> figure (usually more like 2-5%) applies to single core cpu systems.
>
>> One interesting line from that wiki link says that "more sig.
>> difference in apps. that manipulate large amounts of data in-memory."
>> If I get this pc built will be interesting to see.
>
> However, if my experience with a SFF Mini-Q Jetway branded 'bare bones'
> system is anything to go by, it can make a significant difference when
> relying on  built in graphics that uses shared main system memory. In
> fact so much so as to allow the frame rate benchmark figures in the
> Unreal game to get very close to what you'd expect when using a seperate
> plug in AGP MX440 card with its own independent memory (exactly the same
> video chip that's used by the MoBo).
>
> Dual channel operation definitely seems to mitigate the deletorious
> effects of trying to share system memory between the CPU and an on-board
> GPU (but this may only apply when the IGP and MoBo chipset are both made
> by the same manufacturer ;-).
>
> HTH
>
> -- 
> Regards, John.
>
> Please remove the "ohggcyht" before replying.
> The address has been munged to reject Spam-bots.
>

unreal.....the greatest pc game i ever played!!!

Jim E  wrote
>
>unreal.....the greatest pc game i ever played!!!
>
Perhaps this is of interest to you ..?
It was mentioned the other day in alt.comp.freeware that the Unreal
Development Kit has been released into the wild.
Free for non-commercial and educational use. No reg. ~560MB
<http://developer.nvidia.com/object/udk.html>
-- 
Roger Hunt