I am planning to upgrade/change my notebook to new DDR2 SO-DIMM RAM modules.

I have heard that DualChannel capable memory modules could speed up the computer significantly.

Is this true?
How much speed-up can I expect ?

AFAIK the two modules must fit together in order to be able to use CualChannel.

What means "fit"?

Do they have to be the same capacity (e.g. both 1 GB or is a 512 + a 1024 GB combination possible as well?)

Do the two RAM modules have to have ECC feature?

Do the two RAM modules have to have both the same FSB (or is e.g. one 400 Mhz and the other 533Mhz possible) ?

Do the two RAM modules have to be both double sided or single sided ?

Jason

Jason Stacy wrote:

Start by reading the manual for your notebook to see if it supports
dual-channel memory, and to see if it supports DDR2.
--
Cheers, Bob

"Jason Stacy" <jjstacy@yahoo.net> wrote in message
news:47440b62$0$13121$9b4e6d93@newsspool2.arcor-online.net...
Go to,
http://www.crucial.com/
Put in your notebook brand or model number. They will tell you what you can
use and rather you need pairs or not.

"Jason Stacy" <jjstacy@yahoo.net> wrote in message
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Uhm... You can't take out DDR and put in DDR2. The slots aren't compatible.

If you are talking about dual channel, that just means two identical pieces
of memory that the computer shares access across to increase access time. It
can make a small speed improvement, but definately not worth tossing
whatever you have now just to use dual channel.

Yes Dual channel can speed up processes quite a bit, but it depends on what
types of programs you are running.
As far as the FSB speed, it will have to be the same. There are some RAM
sticks that are backwards compatible, but that will go through and be the
slowest. Therefore, if you go with a 400 and a 533, if the 533 is backwards
compatible it will clock itself down to 400, so if thats the case, it would
be more cost efficient to go both 400, but better performance if you go both
533.

"Jason Stacy" <jjstacy@yahoo.net> wrote in message
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"Jason Stacy" <jjstacy@yahoo.net> wrote in message
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If it has 2 identical DIMMs it probably is dual channel, but check the
specs.

The performance hit of using single channel in a dual channel machine is
about 10%.

For dual channel performance, both DIMMs should be identical in all specs,
and from the same manufacturer. You can get dual channel kits.

If you now have 512MB or less and go to 2 x 1GB, you will see a performance
gain from the increased RAM.

My HP laptop has a 533MHz FSB and came with 512MB of 400MHz DDR2.
I upgraded it to 2 GB of 533MHz DDR2, and had a significant performance
increase. Also, the new RAM runs at 533MHz. It uses an Intel 915 Express
chipset.

DDR and DDR2 are different type slots. They may appear alike, but, DDR2
won't physically fit in a DDR slot.

Dual channel is a function of the motherboard and bios capability. To
implement dual channel, the RAM in pairs should be identical. And, you must
use the proper RAM slots. And, you cannot have any other RAM filling
another slot. Any attempt to circumvent that will disable dual channel.

--
Dave
Profound is we're here due to a chance arrangement
of chemicals in the ocean billions of years ago.
More profound is we made it to the top of the food
chain per our reasoning abilities.
Most profound is the denial of why we may
be on the way out.
"Jason Stacy" <jjstacy@yahoo.net> wrote in message
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Jason Stacy wrote:

Not much. Synthetic benchmarks will show a big performance increase, but the
real life experience is much smaller.

Some chipsets made for laptops support dual channel with different modules.
I'm pretty sure the PM965 in my laptop does.

Only if your board needs it. AFAIK ECC and non-ECC modules can't be mixed.

No, but the slowest module will set the speed for all memory modules.

I'm not even sure i've ever seen a single sided DDR 2 module. But get the
same kind. Just in case.

--
Lasse Jensen [fafler at g mail dot com]
Linux, the choice of a GNU generation.

DJason Stacy wrote:
I suspect it is a sign of a lack of personal confidence.

Anyway, I asked my engineer buddies and the response is that to run dual
channel DDR2 you at least need one of the newest units, with dual
channel slots, and dual core processor(s), both modules must be similar
in all respects.

Even then, all agree, you should consult a professional. Also, you
should have a computer expert open your laptop and install any parts.