Simple RAM question

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I'm thinking of expanding my laptops current memmory of 2x256mb to 2x512
which makes a total of 1 gig of memmory. Thing is, are all kinds of
soDIMM compatible? What should I be aware of before buying?

The manual says this:

"256 of 512 MB DDR333 geheugen, uit te breiden tot 1 GB met
gebruik van twee soDIMM modules"

Which means I could upgrade to 1gb, but I have virtually no idea what
the terms DDR333 or PC2600 and the likes mean, while they seem really

Is there anybody who can help me out here?

Thanks in advance, Ewoud.

Re: Simple RAM question

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Whenever I need to buy memory I go to where they have a very easy
menu driven system which helps to identify
suitable memory

Re: Simple RAM question

DDR333 and PC2600 are the same. Memory running at 333 Mhz has a theoretical
bandwidth of 2600 MB/sec. The memory you buy should be this speed or slightly
faster. Memory with a faster speed rating will run at 333 Mhz because that is
the speed of your memory controller. All the SoDIMM modules I have seen at this
speed are DDR, although my laptop has a warning not to use DDR2.

Ewoud van Loon wrote:
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                   Mike Walsh
            West Palm Beach, Florida, U.S.A.

Re: Simple RAM question

On Sun, 01 Jan 2006 17:48:52 +0100, Ewoud van Loon

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Not "all", soDIMM just means (s)mall (o)utline.  There are
PC133 soDIMMs for systems a few years old, for example, and
DDR2 soDIMMs for the newest notebooks, in addition to the
DDR(1) (omit "1" when searching for them) soDIMMs that your
system appears to need.

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That it is soDIMM, that it's DDR, the minimum speed
needed... for example, if your memory bus runs at 166MHz,
you'd need at least PC2700, OR faster.  In other words, the
"PC(nnnn)" rating is a rating of the fastest a module can
run, a bit like car tire speed ratings in that you don't
HAVE to run it that fast, only that it's guaranteed up to
that speed if/when the rest of the system can do so too.

Then there's density, but with 512MB modules I don't think
you have that concern.... I could be wrong though and it is
another reason to buy any memory from someplace with a good
return policy, avoiding the cheapest vendors on
Pricewatch/etc, or other unknown sellers like on ebay.

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PC2700 means it can run UP TO 166MHz, or DDR333 (in double
data rate terms, 166.6 x 2 = 333 ).  Basically it means you
should choose PC2700 or higher (typically PC3200), not
PC2100 or PC1600.  You might as well get PC3200 CL/CAS2.5,
or PC2700 CL/CAS2.  This later spec is the latency, a
smaller number being better, and a few % faster.  Depending
on where you buy the memory, the minor performance
difference may not be worth the cost difference, but for
nearly same cost, go with the lower CL/CAS #.

Re: Simple RAM question


The development of computer systems since their advent has been fast
paced and meticulous. This has created a vast array of differing
systems that require various specifications and types of RAM. It is
important to match the correct RAM modules to your individual system,
for two main reasons. Physically if the memory is incorrect then it
wont actually fit into the computer, secondly if the correct module is
used but it is of incorrect capacity or speed then the systems
operation will be adversely effected.

Types of RAM include the latest DDR, Rambus RDRAM RIMM, laptop memory
SODIMM, and other types like SIMM or EDO. The vast majority of top
performing machines will use either DDR or Rambus memory modules. These
run at very fast bus speeds to match those of processors and

Single in-line memory modules, SIMMs, have a pin count of 72 which have
contacts on one side of the memory module only. DIMMs, dual in-line
memory modules, have since replaced SIMMs and offer a double sided
module. DIMM is the current standard used throughout the computer
industry for DDR and SDRAM.

The first SIMMs had just 30 pins and were used in 386 and 486
computers. These modules used fast page mode. The 30 pin memory modules
were soon replaced by the 72 pin module using fast page mode and either
parity or non parity.

These modules were produced in capacities that are multiples of
4mb,i.e. 8Mb, 16Mb, 32Mb, 64Mb and 128Mb.

2) DDR Memory
DDR ram uses latest technology to deliver a memory chip with
performance to suit the newest CPUs with multi gigahertz clock speeds.
DDR RAM, double data rate, can send data on both the rise and fall of
the clock which has doubled its speed from SDRAM. This development in
ddr ram has allowed memory performance to increase significantly over
the past few years.

Current industry speed standards consist of DDR RAM are PC2100 -
266MHZ, PC2700 - 333MHZ, PC3200 - 400MHZ, by installing the fastest
specification DDR RAM that your motherboard will permit will enhance
your system performance and allow communication between devices in a
shorter period of time. VTec recommend that you have at least 256mb of
DDR RAM for normal use, 512mb or 1gb is essential for computer systems
running intense applications like advanced games or graphics software.
If your Ram module has 184pins then you have DDR RAM - (SDRAM).

Hope this helps in some way.

You can also read this article:

Gary Hendricks

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