Asus P4C800-E Deluxe and 2GB of matched memory

[Mark]

Hi,

There's an awful lot of information about memory these days on the net.
So, you might think that with all of this information available that it
would be a simple matter to purchase memory. However, instead of showing
the path to buying memory, I'm left with clouds of doubt and lots
uncertainty. In fact, I would argue that there is a lot of ambiguous
information available.

Seems I am not alone after reading some of the posts to this group and
in other places. If there is a better location to have asked this
question, please advise.

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

On the surface, I would think, if it's important that Dual Channel
operation require a matching pair of SIMMs for maximizing stability and
performance, then running a matching quad should insured more.

On the other hand, if each dual channel branch is controlled by an
independent RAM controller, then it should be impossible for one set to
see the other set. AFAIK, techincally that is how its suppose to work.
In practice, I'm not so sure.

A poor analogy might be when you go to get four new tires for your car.
You wouldn't want four different tire manufacturers. You wouldn't want
four differnet tire sizes. You wouldn't want four tires that have
different tread patterns. Nor would you want two tires manufactured a
year ago matched with two tires manufactured yesterday. You want four
exact same tires manufactured all at the same time. I warned you it was
a poor analogy.

Anyway, having talked to almost every major player in the memory
business (with the exception of Corsair (which *never* returned my phone
calls and who I would never do business with[1])), four matching 512MB
SIMMs are not important. Of course, they recommended matching pairs.

Even a call to Intel said that it was not important. Tho, they also said
that there was no benefit to having four SIMMs over two. Which is not
true according to the Intel 875P Chipset Memory Configuration Guide
White Paper.

However, OCZ (who would do the testing for free), a couple of the memory
retailers and even some reviews have stated that it is important that
all four SIMMs match to each other.

OCZ recommended:

OCZ DDR PC-3200 Dual Channel Optimized 1GB (2 x 512MB) DDR400 PC3200 EL
(Enhanced Latency) Platinum Edition Memory, Model OCZ4001024ELDCPE-K
Retail kit

So, what's the deal?

Is it, as many places say, not important to have a matching quad? Or, as
OCZ has recommended and is willing to perform, necessary for absolute
stability?

Hell, I don't even know if the above mentioned memory will work fully
populating the memory banks. A call to ASUS suggested that their CVL is
rather outdated. But outdated or not, it shows that some memory will
work with all four banks filled, while other brands can only populate a
single duel channel. Not very encouraging seeing that or hearing that
they leave old lists laying around only to confuse people.

As for overclocking, yeah, maybe, likely a little, later on down the
road. Only can do so much with the 3.0c and I am not an extreme
overclocker. I'm a first time builder who feels they have gotten
themselves in way over their head.


[1] If you can't reach Corsair before buying, I don't want to know what
it would be like afterwards should a RMA is necessary.

 

[Derek Hawkins]

See important notes on page 2-10 of the manual. It's identical pairs per
channel. Seems to answer most of your questions.

Hi,

There's an awful lot of information about memory these days on the net.
So, you might think that with all of this information available that it
would be a simple matter to purchase memory. However, instead of showing
the path to buying memory, I'm left with clouds of doubt and lots
uncertainty. In fact, I would argue that there is a lot of ambiguous
information available.

Seems I am not alone after reading some of the posts to this group and
in other places. If there is a better location to have asked this
question, please advise.

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

On the surface, I would think, if it's important that Dual Channel
operation require a matching pair of SIMMs for maximizing stability and
performance, then running a matching quad should insured more.

On the other hand, if each dual channel branch is controlled by an
independent RAM controller, then it should be impossible for one set to
see the other set. AFAIK, techincally that is how its suppose to work.
In practice, I'm not so sure.

A poor analogy might be when you go to get four new tires for your car.
You wouldn't want four different tire manufacturers. You wouldn't want
four differnet tire sizes. You wouldn't want four tires that have
different tread patterns. Nor would you want two tires manufactured a
year ago matched with two tires manufactured yesterday. You want four
exact same tires manufactured all at the same time. I warned you it was
a poor analogy.

Anyway, having talked to almost every major player in the memory
business (with the exception of Corsair (which *never* returned my phone
calls and who I would never do business with[1])), four matching 512MB
SIMMs are not important. Of course, they recommended matching pairs.

Even a call to Intel said that it was not important. Tho, they also said
that there was no benefit to having four SIMMs over two. Which is not
true according to the Intel 875P Chipset Memory Configuration Guide
White Paper.

However, OCZ (who would do the testing for free), a couple of the memory
retailers and even some reviews have stated that it is important that
all four SIMMs match to each other.

OCZ recommended:

OCZ DDR PC-3200 Dual Channel Optimized 1GB (2 x 512MB) DDR400 PC3200 EL
(Enhanced Latency) Platinum Edition Memory, Model OCZ4001024ELDCPE-K
Retail kit

So, what's the deal?

Is it, as many places say, not important to have a matching quad? Or, as
OCZ has recommended and is willing to perform, necessary for absolute
stability?

Hell, I don't even know if the above mentioned memory will work fully
populating the memory banks. A call to ASUS suggested that their CVL is
rather outdated. But outdated or not, it shows that some memory will
work with all four banks filled, while other brands can only populate a
single duel channel. Not very encouraging seeing that or hearing that
they leave old lists laying around only to confuse people.

As for overclocking, yeah, maybe, likely a little, later on down the
road. Only can do so much with the 3.0c and I am not an extreme
overclocker. I'm a first time builder who feels they have gotten
themselves in way over their head.


[1] If you can't reach Corsair before buying, I don't want to know what
it would be like afterwards should a RMA is necessary.

 

[Paul]

See important notes on page 2-10 of the manual. It's identical pairs per
channel. Seems to answer most of your questions.

The Intel white paper has all the answers. If you are willing to accept
reduced performance, four different DIMMs can operate in "Virtual
Single Channel Mode". So, they don't have to match to be usable.

ftp://download.intel.com/design/chipsets/applnots/25273001.pdf

Page 13 of the guide gives a prioritized performance list, showing
which configuration gives the best performance. If you check over on
abxzone.com, there are people there who have noticed other aspects to
getting the last bit of performance. You might find, for example, that
the memory timings have to be relaxed to get four sticks to run.
You'll have to read thousands of posts to get a full picture of the
issues - the best I've seen over there, was someone got four sticks
running at DDR440.

HTH,
Paul

Hi,

There's an awful lot of information about memory these days on the net.
So, you might think that with all of this information available that it
would be a simple matter to purchase memory. However, instead of showing
the path to buying memory, I'm left with clouds of doubt and lots
uncertainty. In fact, I would argue that there is a lot of ambiguous
information available.

Seems I am not alone after reading some of the posts to this group and
in other places. If there is a better location to have asked this
question, please advise.

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

On the surface, I would think, if it's important that Dual Channel
operation require a matching pair of SIMMs for maximizing stability and
performance, then running a matching quad should insured more.

On the other hand, if each dual channel branch is controlled by an
independent RAM controller, then it should be impossible for one set to
see the other set. AFAIK, techincally that is how its suppose to work.
In practice, I'm not so sure.

A poor analogy might be when you go to get four new tires for your car.
You wouldn't want four different tire manufacturers. You wouldn't want
four differnet tire sizes. You wouldn't want four tires that have
different tread patterns. Nor would you want two tires manufactured a
year ago matched with two tires manufactured yesterday. You want four
exact same tires manufactured all at the same time. I warned you it was
a poor analogy.

Anyway, having talked to almost every major player in the memory
business (with the exception of Corsair (which *never* returned my phone
calls and who I would never do business with[1])), four matching 512MB
SIMMs are not important. Of course, they recommended matching pairs.

Even a call to Intel said that it was not important. Tho, they also said
that there was no benefit to having four SIMMs over two. Which is not
true according to the Intel 875P Chipset Memory Configuration Guide
White Paper.

However, OCZ (who would do the testing for free), a couple of the memory
retailers and even some reviews have stated that it is important that
all four SIMMs match to each other.

OCZ recommended:

OCZ DDR PC-3200 Dual Channel Optimized 1GB (2 x 512MB) DDR400 PC3200 EL
(Enhanced Latency) Platinum Edition Memory, Model OCZ4001024ELDCPE-K
Retail kit

So, what's the deal?

Is it, as many places say, not important to have a matching quad? Or, as
OCZ has recommended and is willing to perform, necessary for absolute
stability?

Hell, I don't even know if the above mentioned memory will work fully
populating the memory banks. A call to ASUS suggested that their CVL is
rather outdated. But outdated or not, it shows that some memory will
work with all four banks filled, while other brands can only populate a
single duel channel. Not very encouraging seeing that or hearing that
they leave old lists laying around only to confuse people.

As for overclocking, yeah, maybe, likely a little, later on down the
road. Only can do so much with the 3.0c and I am not an extreme
overclocker. I'm a first time builder who feels they have gotten
themselves in way over their head.


[1] If you can't reach Corsair before buying, I don't want to know what
it would be like afterwards should a RMA is necessary.

 

[Mark]

See important notes on page 2-10 of the manual. It's identical pairs
per channel. Seems to answer most of your questions.

According to the manual (the section you mentioned above) it doesn't
even say a matched pair. A matched pair is more then just the same type
and size. So I would say that the answer is not my omission and can't be
found in the manual.

Thanks for the reply tho.

 

[Z Man]

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

I am running 4x1G PC2100 DDR, for a total of 3.49GB. I bought the memory
from a couple of Ebay vendors, and it works great. Three sticks are from one
vendor (not all purchased as the same time), and the 4th from another
vendor. All that agonizing over memory issues be not really be necessary.

 

[Derek Hawkins]

Get two matched (what ever you consider that to be) pairs and cut the
comedy.

 

[Mark]

On Dec 04 2003, Derek Hawkins wrote:

Get two matched (what ever you consider that to be) pairs

Why is it that I get the impression that you are just reiterating what
you already wrote above without including any additional reasoning. The
manual does not have the answer. Oddly, in the manual the word "pair"
appears twice and the word "match" appears four times, but never
together. There is no occurrences of the word "matched" and the word
"identical" in its memory context is meaningless as it pertains to my
initial post.

Just because something will work doesn't mean that it is the most ideal
way to do something. The Intel 875P Chipset Memory Configuration Guide
White Paper that I mentioned before explains the differences between
different types of memory configurations except one, the questions I
raised. Yet, the ones explained within all work to different results.

I'm sorry, but answering "Get two matched pairs" without addressing free
quad matching is not an answer. If you don't know the answer, then
that's cool, I can understand that. Perhaps this is the first time you
have heard of quad matching. Whichever the case may be, I thank you for
your time.

I'm not trying to be combative. I was truly hoping that replies would be
informative and descriptive. Perhaps personal experience instead of a
vague reference from a mainboard manual which, as I pointed out already,
doesn't address the questions I raised in my initial post.

and cut the comedy.

I fail to see what you found comical in my reply to you. Hopefully, I've
addressed that issue for you in this reply.

 

[sheer]

Are you the bloke in the Fawlty Towers episode who sells spoons?

Hi,

There's an awful lot of information about memory these days on the net.
So, you might think that with all of this information available that it
would be a simple matter to purchase memory. However, instead of showing
the path to buying memory, I'm left with clouds of doubt and lots
uncertainty. In fact, I would argue that there is a lot of ambiguous
information available.

Seems I am not alone after reading some of the posts to this group and
in other places. If there is a better location to have asked this
question, please advise.

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

On the surface, I would think, if it's important that Dual Channel
operation require a matching pair of SIMMs for maximizing stability and
performance, then running a matching quad should insured more.

On the other hand, if each dual channel branch is controlled by an
independent RAM controller, then it should be impossible for one set to
see the other set. AFAIK, techincally that is how its suppose to work.
In practice, I'm not so sure.

A poor analogy might be when you go to get four new tires for your car.
You wouldn't want four different tire manufacturers. You wouldn't want
four differnet tire sizes. You wouldn't want four tires that have
different tread patterns. Nor would you want two tires manufactured a
year ago matched with two tires manufactured yesterday. You want four
exact same tires manufactured all at the same time. I warned you it was
a poor analogy.

Anyway, having talked to almost every major player in the memory
business (with the exception of Corsair (which *never* returned my phone
calls and who I would never do business with[1])), four matching 512MB
SIMMs are not important. Of course, they recommended matching pairs.

Even a call to Intel said that it was not important. Tho, they also said
that there was no benefit to having four SIMMs over two. Which is not
true according to the Intel 875P Chipset Memory Configuration Guide
White Paper.

However, OCZ (who would do the testing for free), a couple of the memory
retailers and even some reviews have stated that it is important that
all four SIMMs match to each other.

OCZ recommended:

OCZ DDR PC-3200 Dual Channel Optimized 1GB (2 x 512MB) DDR400 PC3200 EL
(Enhanced Latency) Platinum Edition Memory, Model OCZ4001024ELDCPE-K
Retail kit

So, what's the deal?

Is it, as many places say, not important to have a matching quad? Or, as
OCZ has recommended and is willing to perform, necessary for absolute
stability?

Hell, I don't even know if the above mentioned memory will work fully
populating the memory banks. A call to ASUS suggested that their CVL is
rather outdated. But outdated or not, it shows that some memory will
work with all four banks filled, while other brands can only populate a
single duel channel. Not very encouraging seeing that or hearing that
they leave old lists laying around only to confuse people.

As for overclocking, yeah, maybe, likely a little, later on down the
road. Only can do so much with the 3.0c and I am not an extreme
overclocker. I'm a first time builder who feels they have gotten
themselves in way over their head.


[1] If you can't reach Corsair before buying, I don't want to know what
it would be like afterwards should a RMA is necessary.

 

[Mark]

The Intel white paper has all the answers. If you are willing to
accept reduced performance, four different DIMMs can operate in
"Virtual Single Channel Mode". So, they don't have to match to be
usable.

Right, but that is one of the worse configuration you can have and
should be avoided if possible. The system will (should) adjust to the
slowest installed memory provided that there are no problems with the
SPD on the DIMMs. It should work, although it is not ideal.

In my case, I have the option of getting four matched OCZ EL DDR PC-3200
Dual Channel Platinum sticks. Although, to be fair, the concern isn't
all about the tests, but also the brand and model of memory.

Unfortunately, Intel 875P Chipset White Paper doesn't address memory
that is quad matched, just paired. Something they were not aware of at
the time of publication.

Page 13 of the guide gives a prioritized performance list, showing
which configuration gives the best performance. If you check over on
abxzone.com, there are people there who have noticed other aspects to
getting the last bit of performance.

That is what I believe the OCZ tested DIMMs would provide. However, is
OCZ EL DDR PC-3200 Dual Channel Platinum's the memory that should have
these test performed? While OCZ is the only company willing to offer the
tests, it's possible another brand might be a better choice and just
needs a little persuasion.

You might find, for example, that the memory timings have to be
relaxed to get four sticks to run. You'll have to read thousands of
posts to get a full picture of the issues - the best I've seen over
there, was someone got four sticks running at DDR440.

I'll look over that the URL you listed. Thanks for the direction.

 

[Mark]

I am running 4x1G PC2100 DDR, for a total of 3.49GB.

Is that normal for the system overhead to eating up ~512MB of your
installed memory? As I understand, there is always system overhead which
uses part of your total available RAM, but that seems like a lot of
overhead.

I bought the memory from a couple of Ebay vendors, and it works great.
Three sticks are from one vendor (not all purchased as the same time),
and the 4th from another vendor. All that agonizing over memory
issues be not really be necessary.

It's true that you can use mixed memory and have the system work. It is,
however, also true that mixed memory is not the most ideal
configuration.

In my case, OCZ is the only memory company willing to do DIMM tests to
determine 4 matching sticks. They will do these test using the OCZ EL
DDR PC-3200 Dual Channel Platinum memory and create a customized 4 DIMM
kit of matching memory.

One question I kept asking myself was why would OCZ offer these tests,
while all the other memory companies felt the tests were unnecessary?

Could it be that OCZ memory is generally weak compared to the other
memory companies, and this is their way of insuring a good result with a
customer?

Could it be that the other companies do not offer it because it would be
difficult handling so many requests?

But the mention of matched quads isn't only from OCZ. It is mentioned,
for example, at anandtech.

I probably didn't phrase my initial questions as clear as I could have.
Perhaps to have re-written it, I would have made it clearer which is the
better path to purse - OCZ PC3200 with 4 matching sticks, or some other
brand with two matching pairs of PC3200 (or PC3500 or PC3700 or which
one)?

Maybe even that doesn't really make it as clear as it should be, it's
late and I should have been asleep 5 hours ago.

Thanks for the feedback.

 

[Derek Hawkins]

Get both the matched quad and the two matched pairs, test them nine ways to
Sunday then tell which is better.

 

[Winston Smith]

Mark,

Haven't read your entire article, I bought the 2X 512MB Corsair 3500C2
sticks, I must say that the sytem (P4P800 Deluxe) is rock solid stable,
never had a problem with it, down here in Australia the only choice seems to
be Kingston, Corsair & the cheaper generic memory.

My next system will be ASUS P4C800-E with the Corsair modules again which
are painfully expensive beasts at $AU320- per module, let me know how it
goes with OCZ memory.

Ben.

Hi,

There's an awful lot of information about memory these days on the net.
So, you might think that with all of this information available that it
would be a simple matter to purchase memory. However, instead of showing
the path to buying memory, I'm left with clouds of doubt and lots
uncertainty. In fact, I would argue that there is a lot of ambiguous
information available.

Seems I am not alone after reading some of the posts to this group and
in other places. If there is a better location to have asked this
question, please advise.

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

On the surface, I would think, if it's important that Dual Channel
operation require a matching pair of SIMMs for maximizing stability and
performance, then running a matching quad should insured more.

On the other hand, if each dual channel branch is controlled by an
independent RAM controller, then it should be impossible for one set to
see the other set. AFAIK, techincally that is how its suppose to work.
In practice, I'm not so sure.

A poor analogy might be when you go to get four new tires for your car.
You wouldn't want four different tire manufacturers. You wouldn't want
four differnet tire sizes. You wouldn't want four tires that have
different tread patterns. Nor would you want two tires manufactured a
year ago matched with two tires manufactured yesterday. You want four
exact same tires manufactured all at the same time. I warned you it was
a poor analogy.

Anyway, having talked to almost every major player in the memory
business (with the exception of Corsair (which *never* returned my phone
calls and who I would never do business with[1])), four matching 512MB
SIMMs are not important. Of course, they recommended matching pairs.

Even a call to Intel said that it was not important. Tho, they also said
that there was no benefit to having four SIMMs over two. Which is not
true according to the Intel 875P Chipset Memory Configuration Guide
White Paper.

However, OCZ (who would do the testing for free), a couple of the memory
retailers and even some reviews have stated that it is important that
all four SIMMs match to each other.

OCZ recommended:

OCZ DDR PC-3200 Dual Channel Optimized 1GB (2 x 512MB) DDR400 PC3200 EL
(Enhanced Latency) Platinum Edition Memory, Model OCZ4001024ELDCPE-K
Retail kit

So, what's the deal?

Is it, as many places say, not important to have a matching quad? Or, as
OCZ has recommended and is willing to perform, necessary for absolute
stability?

Hell, I don't even know if the above mentioned memory will work fully
populating the memory banks. A call to ASUS suggested that their CVL is
rather outdated. But outdated or not, it shows that some memory will
work with all four banks filled, while other brands can only populate a
single duel channel. Not very encouraging seeing that or hearing that
they leave old lists laying around only to confuse people.

As for overclocking, yeah, maybe, likely a little, later on down the
road. Only can do so much with the 3.0c and I am not an extreme
overclocker. I'm a first time builder who feels they have gotten
themselves in way over their head.


[1] If you can't reach Corsair before buying, I don't want to know what
it would be like afterwards should a RMA is necessary.

 

[Z Man]

Is that normal for the system overhead to eating up ~512MB of your
installed memory? As I understand, there is always system overhead which
uses part of your total available RAM, but that seems like a lot of
overhead.

With 3GB I lost no memory to overhead, but with 4G I lost almost half. The
manual mentions that with 4G some loss will be seen, but this is quite a bit
more than I expected. It is almost not worth using up one stick to get only
half that much incremental memory.

 

[Armin Pfeffer]

With 3GB I lost no memory to overhead, but with 4G I lost almost half. The
manual mentions that with 4G some loss will be seen, but this is quite a bit
more than I expected. It is almost not worth using up one stick to get only
half that much incremental memory.

Please read the WIndows papers regarding thi sissue!. You loose
everything above 3.49 GB because of the PCI adress room starting here.
It is nothing sused up by overhead but not visible because of adresses
used for other devices.
HTH
Armin

 

[Paul]

Right, but that is one of the worse configuration you can have and
should be avoided if possible. The system will (should) adjust to the
slowest installed memory provided that there are no problems with the
SPD on the DIMMs. It should work, although it is not ideal.

In my case, I have the option of getting four matched OCZ EL DDR PC-3200
Dual Channel Platinum sticks. Although, to be fair, the concern isn't
all about the tests, but also the brand and model of memory.

Unfortunately, Intel 875P Chipset White Paper doesn't address memory
that is quad matched, just paired. Something they were not aware of at
the time of publication.


That is what I believe the OCZ tested DIMMs would provide. However, is
OCZ EL DDR PC-3200 Dual Channel Platinum's the memory that should have
these test performed? While OCZ is the only company willing to offer the
tests, it's possible another brand might be a better choice and just
needs a little persuasion.


I'll look over that the URL you listed. Thanks for the direction.

The Intel concept was named "Uber DIMM" by somebody, and the claim is
that a DIMM in Channel A and a DIMM in Channel B, are read simultaneously,
as if they were 128 bits wide. An ordinary DIMM has 64 data bits, so
the "Uber DIMM" title was supposed to bring visions of the two DIMMs
being cemented together.

What that means is, for the best data transfer performance, the DIMM
characteristics only have to be paired. Where an additional advantage
comes in for quad matching, is the transmission line impedance of the
DIMMs end up all being the same, whereas if you bought two Kingston
sticks and two Crucial sticks, they might be slightly different. This
might make a difference if you were trying to reach DDR440, but might
not if you were running at stock speed.

So, the following should give good performance:

Channel A Channel B
1GB DS (16) 64Mx8 chips 1GB DS (16) 64Mx8 chips
512MB DS (16) 32Mx8 chips 512MB DS (16) 32Mx8 chips

Since all modules are double sided, that maximizes the number of banks
that can be interleaved, and you'd get the same Sandra memory bench
as with this configuration:

Channel A Channel B
1GB DS (16) 64Mx8 chips 1GB DS (16) 64Mx8 chips
1GB DS (16) 64Mx8 chips 1GB DS (16) 64Mx8 chips

In this last case, the Northbridge needs to reserve some address space
for the PCI/AGP bridges, and that is why 512MB is "lost" from a 4GB
configuration.

HTH,
Paul

 

[Z Man]

In this last case, the Northbridge needs to reserve some address space
for the PCI/AGP bridges, and that is why 512MB is "lost" from a 4GB
configuration.

Paul, are you saying that the maximum memory you can have is about three and
one half GB? That doesn't seem reasonable...

How much would you loose if you had eight GB of memory? As I said
previously, I am using up one stick for one half the 'bang for the buck'. I
feel foolish, having been around long enough to remember when 8MB of memory
was considered a lot

 

[Robert Hancock]

You'll probably have to enable PAE in the operating system to see all the
RAM in that case. I think in Windows it's a command line switch in the
boot.ini file somewhere..

 

[Paul]

Paul, are you saying that the maximum memory you can have is about three and
one half GB? That doesn't seem reasonable...

How much would you loose if you had eight GB of memory? As I said
previously, I am using up one stick for one half the 'bang for the buck'. I
feel foolish, having been around long enough to remember when 8MB of memory
was considered a lot

When I look in the Pentium 4 spec sheet, it says the address bus effectively
has 36 bits. That means the processor itself can address a space much
larger than 4GB. The address bus has A35:A3 address signals.

The 875 Northbridge datasheet says:

"32-bit addressing for access to 4 GB of memory space"

http://developer.intel.com/design/chipsets/datashts/25252501.pdf

The Northbridge has A31:A3 address signals, which means not all the
processor address signals get connected. There are five attribute signals
(and I cannot find a definition of what they do) and AFAIK these are used
for things like cache coherency and the like. My guess is that using the
875 Northbridge means 4GB is the maximum physical address space.

In section 3.5.33 on page 70 of 25252501.pdf, there is a register
in the Northbridge called TOUD "Top Of Used DRAM". The calculation
for the value to be stored in this register is stated to be:

"To calculate the value of TOUD, configuration software should set
this value to the smaller of the following two cases:
* The maximum amount of usable memory in the system minus optional tseg.
* The address allocated for PCI memory or the graphics aperture
minus optional tseg.
NOTE: Even if the OS does not need any PCI space, TOUD should never
be programmed above 0xFEC0_0000h. If TOUD is programmed above this,
address ranges that are reserved will become accessible to
applications."

Even if the wording is a little confused, the essence of that section
suggests the PCI/AGP spaces prevent all the DRAM from being used.

If you want to experiment, you could try reducing the AGP aperture in
the BIOS, and see if the memory available in Windows is increased
slightly. Removing an AGP video card if installed, and using a PCI
card should also help, as that would negate the need for an AGP
aperture. That magic hexidecimal number in the quote above, is 20MB
from the top of memory, so if all PCI and AGP devices were removed
and the BIOS was beaten into submission, then 4GB minus 20MB would
be the maximum allowed.

I saw Robert's post about PAE, and a quick search suggests it covers
a different aspect of huge memory, that of balancing the needs of
the OS versus an application. Even if you use PAE, that doesn't
guarantee that a given application was written properly to use large
amounts of memory. (On a Unix system, I used to use a malloc loop
in C to test exactly how much memory I could get - of course freeing
the memory when done. I don't know how difficult that simple program
would be in Windows )

HTH,
Paul

 

[Mox 13]

Winston

I am considering buying the P4C800-E Deluxe. Since you are using Corsair
3500C2 I would like to ask you a question. On the memory compatibility sheet
it looked like you could only use 2 of the memory slots when using Corsair.
Do you know if that is true? I already have 1 stick of 256MB Corsair 3500C2
and was thinking of just getting another 256MB stick to match it to start
with. Then later adding 2X 512MB Corsair 3500C2. Does that sound like it
would work?

Thanks
Mox

Mark,

Haven't read your entire article, I bought the 2X 512MB Corsair 3500C2
sticks, I must say that the sytem (P4P800 Deluxe) is rock solid stable,
never had a problem with it, down here in Australia the only choice seems to
be Kingston, Corsair & the cheaper generic memory.

My next system will be ASUS P4C800-E with the Corsair modules again which
are painfully expensive beasts at $AU320- per module, let me know how it
goes with OCZ memory.

Ben.

Hi,

There's an awful lot of information about memory these days on the net.
So, you might think that with all of this information available that it
would be a simple matter to purchase memory. However, instead of showing
the path to buying memory, I'm left with clouds of doubt and lots
uncertainty. In fact, I would argue that there is a lot of ambiguous
information available.

Seems I am not alone after reading some of the posts to this group and
in other places. If there is a better location to have asked this
question, please advise.

I want to buy 2 GBs of RAM for the ASUS P4C800-E Deluxe motherboard. The
biggest sticking point has been over whether FOUR matching 512MB SIMMs
are needed. I'm not referring to buying two kits of 1 GB duel channel
memory (matching pairs), but that /all/ four sticks match to each other
(matching quad).

On the surface, I would think, if it's important that Dual Channel
operation require a matching pair of SIMMs for maximizing stability and
performance, then running a matching quad should insured more.

On the other hand, if each dual channel branch is controlled by an
independent RAM controller, then it should be impossible for one set to
see the other set. AFAIK, techincally that is how its suppose to work.
In practice, I'm not so sure.

A poor analogy might be when you go to get four new tires for your car.
You wouldn't want four different tire manufacturers. You wouldn't want
four differnet tire sizes. You wouldn't want four tires that have
different tread patterns. Nor would you want two tires manufactured a
year ago matched with two tires manufactured yesterday. You want four
exact same tires manufactured all at the same time. I warned you it was
a poor analogy.

Anyway, having talked to almost every major player in the memory
business (with the exception of Corsair (which *never* returned my phone
calls and who I would never do business with[1])), four matching 512MB
SIMMs are not important. Of course, they recommended matching pairs.

Even a call to Intel said that it was not important. Tho, they also said
that there was no benefit to having four SIMMs over two. Which is not
true according to the Intel 875P Chipset Memory Configuration Guide
White Paper.

However, OCZ (who would do the testing for free), a couple of the memory
retailers and even some reviews have stated that it is important that
all four SIMMs match to each other.

OCZ recommended:

OCZ DDR PC-3200 Dual Channel Optimized 1GB (2 x 512MB) DDR400 PC3200 EL
(Enhanced Latency) Platinum Edition Memory, Model OCZ4001024ELDCPE-K
Retail kit

So, what's the deal?

Is it, as many places say, not important to have a matching quad? Or, as
OCZ has recommended and is willing to perform, necessary for absolute
stability?

Hell, I don't even know if the above mentioned memory will work fully
populating the memory banks. A call to ASUS suggested that their CVL is
rather outdated. But outdated or not, it shows that some memory will
work with all four banks filled, while other brands can only populate a
single duel channel. Not very encouraging seeing that or hearing that
they leave old lists laying around only to confuse people.

As for overclocking, yeah, maybe, likely a little, later on down the
road. Only can do so much with the 3.0c and I am not an extreme
overclocker. I'm a first time builder who feels they have gotten
themselves in way over their head.


[1] If you can't reach Corsair before buying, I don't want to know what
it would be like afterwards should a RMA is necessary.