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Posted by Tristan Miller on March 4, 2006, 8:21 pm
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Greetings.
I've got a Samsung X20 laptop which I am considering giving a memory
upgrade. The user guide states only the following with regard to the type
of memory required:
> Memory: 256/512/1024 MB DDR2 SDRAM, 2 DDR socket
I did some Internet window-shopping and note that this memory is available
at different clock speeds -- 512 MB @ 333 MHz or 512 MB @ 266 MHz, for
example.
Does it matter what the clock speed of the memory chips are? Can I mix and
match, or do both the installed chips have to be running at the same clock
speed?
Regards,
Tristan
--
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_V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
(7_\ http://www.nothingisreal.com/ >< To finish what you
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Posted by Barry Watzman on March 4, 2006, 10:18 pm
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Yes, it matters, although a memory module made for a speed faster than
the computer is running at will normally work ok. A memory module made
for a slower speed either will not work at all, or it will work but this
will be accomplished by slowing down the entire memory system to match
the slower memory.
Mix and match? Yes it will work, but: If you mix memory modules on a
machine that is capable of dual channel operation, it will revert to a
single channel mode, cutting the memory subsystem throughput in half.
[See my thread a few days ago about "dual channel memory"]. For proper
dual channel operation, although the modules need not be truly
identical, both their architecture (including their internal
architecture, which you normally have no way of determining] and ALL of
the timing specs must be identical. Also, if you mix different speeds,
not only will you disable dual-channel operation, but the entire memory
system will operate at the speed of the slowest of the two memory
modules (and if that is lower than the "normal" speed of that
CPU/chipset, there is a chance that it won't operate at all, but more
commonly it just slows the system down to match the memory).
Tristan Miller wrote:
> Greetings.
>
> I've got a Samsung X20 laptop which I am considering giving a memory
> upgrade. The user guide states only the following with regard to the type
> of memory required:
>
>
>>Memory: 256/512/1024 MB DDR2 SDRAM, 2 DDR socket
>
>
> I did some Internet window-shopping and note that this memory is available
> at different clock speeds -- 512 MB @ 333 MHz or 512 MB @ 266 MHz, for
> example.
>
> Does it matter what the clock speed of the memory chips are? Can I mix and
> match, or do both the installed chips have to be running at the same clock
> speed?
>
> Regards,
> Tristan
>
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Posted by Tristan Miller on March 4, 2006, 11:43 pm
Please log in for more thread options Greetings.
Thanks for your helpful explanation. I do have some further questions,
though.
>> Does it matter what the clock speed of the memory chips are?
>
> For proper
> dual channel operation, although the modules need not be truly
> identical, both their architecture (including their internal
> architecture, which you normally have no way of determining] and ALL of
> the timing specs must be identical.
Do the memory capacities also have to be identical? That is, can I use one
512 MB chip and one 1024 MB chip?
And how would I go about determining the specs for my existing RAM chips,
if there's no "normal" way of doing it? Would it be indicated on the
chips themselves? Or must I write to Samsung, the manufacturer of my
laptop?
Regards,
Tristan
--
_
_V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
(7_\ http://www.nothingisreal.com/ >< To finish what you
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Posted by Barry Watzman on March 5, 2006, 1:35 am
Please log in for more thread options You can mix capacities, but if you do so you definitely preclude
dual-channel memory system operation. In precluding such operation, you
may be cutting the memory system speed in half. [However, not all
computers can run dual channel interleaved memory anyway, without regard
to whether the modules are matched or not.]
There is no easy way for an end-user to determine all of the relevant
specs for his memory modules. If your system doesn't support dual
channel operation anyway, then you can just ignore most of the specs and
get any module of any size of the right type (SDRAM, DDR, DDR2) and fast
enough to allow full speed operation of the computer (again, if you mix
speeds, at best the memory system will run at the speed of the slowest
module).
If your system does support dual channel operation and your objective is
enable such operation, the best way for an end-user to do this is by
obtaining two identical modules (usually by purchasing them together at
the same time from the same dealer).
The next best option (again, see my earlier post and response on dual
channel memory) is to TRY to obtain a non-identical module which is the
same in all of the ways that matter. In this regard, on some modules
the adhesive part number label has a lot of detailed information (I was
lucky, in my case it did), but in other cases the label is essentially
useless.
If you cannot determine the necessary specs from the module label, it
may be possible to determine them from the actual part numbers on the
chips theselves by finding the chip manufacturer's data sheet for those
particular parts (I'm talking here about the chips on the module, not
the module itself). The data sheets are usually available online,
however, this is ***WAY*** beyond the ability of 95%+ of all computer
owners. In that case, the best thing to do may, again, be to replace
both modules and just sell the removed single module on E-Bay.
Tristan Miller wrote:
> Greetings.
>
> Thanks for your helpful explanation. I do have some further questions,
> though.
>
>
>>>Does it matter what the clock speed of the memory chips are?
>>
>>For proper
>>dual channel operation, although the modules need not be truly
>>identical, both their architecture (including their internal
>>architecture, which you normally have no way of determining] and ALL of
>>the timing specs must be identical.
>
>
> Do the memory capacities also have to be identical? That is, can I use one
> 512 MB chip and one 1024 MB chip?
>
> And how would I go about determining the specs for my existing RAM chips,
> if there's no "normal" way of doing it? Would it be indicated on the
> chips themselves? Or must I write to Samsung, the manufacturer of my
> laptop?
>
> Regards,
> Tristan
>
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Posted by Tristan Miller on March 5, 2006, 3:25 am
Please log in for more thread options Greetings.
> You can mix capacities, but if you do so you definitely preclude
> dual-channel memory system operation. In precluding such operation, you
> may be cutting the memory system speed in half. [However, not all
> computers can run dual channel interleaved memory anyway, without regard
> to whether the modules are matched or not.]
So how do I know whether my system (a Samsung X20) can run dual channel
interleaved memory? I don't see any specific mention of it one way or
another in the spec sheet.
Regards,
Tristan
--
_
_V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
(7_\ http://www.nothingisreal.com/ >< To finish what you
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