memory

[Brian Foster]

If I place a PC-133 SDRAM memory module onto a P-III mobo which lists PC-100
memory to be used with it, will the newer stick work?
Thanks.

 

[S.Heenan]

If I place a PC-133 SDRAM memory module onto a P-III mobo which lists
PC-100 memory to be used with it, will the newer stick work?
Thanks.

It depends on the memory controller. While PC133 SDRAM can always run at
100MHz, the memory controller may have a problem with high density chips.
IOW, it may only "see" half the capacity of the module. If you know the
maker, model number and PCB revision number of the motherboard, you can use
the Memory Selector at www.crucial.com, or post back with that information.

 

[Wolfi]

It depends on the memory controller. While PC133 SDRAM can always run at
100MHz, the memory controller may have a problem with high density chips.
IOW, it may only "see" half the capacity of the module. If you know the

I have to intervene here, since I recently was going through a similar process.
This talking about "high" or "low" density memory modules or chips is just
nonsense, assumable by ignorant marketing and sales people, because they are
not able to explain, what they mean by it and to which datasheet specs it
should point to.

If you are looking at memory chip datasheets, you won't find a
classification named "high" or "low" density, but one that describes 128Mbit
chips and 265Mbit chips.

The first one always works with older and new(er) chipsets, since it uses
4k(=4096=2^12) rows for its cell array, usually referred to as 4k row
refresh cycle.
For 128MByte or 256MB modules you need those built with 8 or 16 pieces of
128Mb chips, internally organised as 16M(=4M(=4k x 1k) x 4banks)x 8bit.
Larger ones are not available with 4k refresh. So if your mobo manual says,
that 256MB is the largest module size you can use, you need these.

The newer, larger 256Mbit chips have 8k(=8192=2^13) rows and therefore use
an 8k row refresh cycle, which has to be performed at twice the speed as the
for the 4k types.
Your chipset must be a newer one to be able to address those 8k row address
lines in order to address the full memory density of a module, built with
those chips, or to work at all in your system.
These 256Mb ones are internally organised as 32M(=8M(=8k x 1k) x 4banks)x 8bit.
If your mobo manual tells you, that you can use 512MB or even larger
modules, than you don't need to care about 4k or 8k and just get the best deal.

So you need to precisely ask for what you need:
4k refresh cycle, which always is 16Mx8
or
8k refresh cycle, which usually is 32Mx8
are the only relevant specs besides module type/form: PC100 or PC133 SDRAM
and density: 128MByte or 256MB.

If you check online stores or Pricewatch or similar, there is a lot of crap
und incorrect things stated, like "32x4 and not 16x8" or "32x8" or "32x64",
which all is wrong in one way or another and if you call and ask those
companies, none of them I tried, could tell me, what exactly they are
selling and what their fantasy specs put on the website actually means in
respect to the correct terms and numbers in the datsheets. They all have
been more or less ignorant and uneducated and started to fantasise in their
try to explain things, they didn't really understand.

I hope you now got a better understanding of what you need to ask for and
where to stay away from and are not totally confused by now ;-)

Wolfi

 

[kony]

I have to intervene here, since I recently was going through a similar process.
This talking about "high" or "low" density memory modules or chips is just
nonsense, assumable by ignorant marketing and sales people, because they are
not able to explain, what they mean by it and to which datasheet specs it
should point to.

If you are looking at memory chip datasheets, you won't find a
classification named "high" or "low" density, but one that describes 128Mbit
chips and 265Mbit chips.

The first one always works with older and new(er) chipsets, since it uses
4k(=4096=2^12) rows for its cell array, usually referred to as 4k row
refresh cycle.
For 128MByte or 256MB modules you need those built with 8 or 16 pieces of
128Mb chips, internally organised as 16M(=4M(=4k x 1k) x 4banks)x 8bit.
Larger ones are not available with 4k refresh. So if your mobo manual says,
that 256MB is the largest module size you can use, you need these.

The newer, larger 256Mbit chips have 8k(=8192=2^13) rows and therefore use
an 8k row refresh cycle, which has to be performed at twice the speed as the
for the 4k types.
Your chipset must be a newer one to be able to address those 8k row address
lines in order to address the full memory density of a module, built with
those chips, or to work at all in your system.
These 256Mb ones are internally organised as 32M(=8M(=8k x 1k) x 4banks)x 8bit.
If your mobo manual tells you, that you can use 512MB or even larger
modules, than you don't need to care about 4k or 8k and just get the best deal.

So you need to precisely ask for what you need:
4k refresh cycle, which always is 16Mx8
or
8k refresh cycle, which usually is 32Mx8
are the only relevant specs besides module type/form: PC100 or PC133 SDRAM
and density: 128MByte or 256MB.

If you check online stores or Pricewatch or similar, there is a lot of crap
und incorrect things stated, like "32x4 and not 16x8" or "32x8" or "32x64",
which all is wrong in one way or another and if you call and ask those
companies, none of them I tried, could tell me, what exactly they are
selling and what their fantasy specs put on the website actually means in
respect to the correct terms and numbers in the datsheets. They all have
been more or less ignorant and uneducated and started to fantasise in their
try to explain things, they didn't really understand.

I hope you now got a better understanding of what you need to ask for and
where to stay away from and are not totally confused by now ;-)

Wolfi

I think a lot of people who didn't already know what they needed,
would find it hard enough to even ask for memory using above specs,
let alone find a CSR or salesperson who knew.

Although "hi" and "low" density is a bit arbitrary, it serves to
distinguish that there are two distinctly different types in the
(256MB) modules most commonly bought for PCs, tried, and returned to
seller when there's a no-post or half-capacity-seen problem.

I recall a point when most PC133 memory was the 16x8 type, making it
easy for buyers to "accidentally" buy a compatible module, but over a
year ago most all modules available on the market in "PC133" spec had
switched to being 32x8, often with no noticable difference on the
packaging for more popular brands in the US retail sector like
Kingston and PNY. Also I've noted that the "low density" 16x8 modules
are usually packaged as "PC100" now, even though almost all are fully
capable of 133MHz operation or beyond, making it seem as though the
major brands have followed a trend in which they label the memory as
"PC100" to imply that it's 16x8, which of course even adds to the
confusion, but may give buyers a hint at what they're getting when the
salesperson can't help.

My comments aren't necessarily meant for you, but this seemed a good
point in the thread to interject them.


Dave