Can't run memory in dual mode

[KenV]

I have a P4P800E Deluxe, P4 2.8c 800FSB, with a 512mb Crucial Micron DDR
PC2700 333mhz CL2.5 DIMM in each of the blue slots.

The BIOS is on the default settings with SPD DRAM timing enabled.

The memory chips were /supposed/ to be identical, but on the ASUS Probe it
gives one as 512 MB Double-bank RAS1 and RAS2, and the other as 512mb Single
Bank, RAS5 and RAS4

When I boot up it says it is running at 266 instead of 333 (or 320) in
single rather than dual channel mode. I changed the memory timing to 320 but
that doesn't seem to do anything.

When I run the CUPID CPU-Z diagnostic program, it shows each of the memory
modules in slots 1 and 3 respectively, gives the same values for each, It
says it is running in single channel mode and gives a frequency of 160mhz.

This is way beyond my level of tech knowledge. Is it that I need identical
chips? Are my settings wrong? Am I losing anything important in this
configuration?

Thanks.

Ken

 

[Custom Computers]

You need identical sticks of memory for it to work, and it needs to be
enabled in the motherboard BIOS. Make sure Performace Mode is set to
enabled.

 

[KenV]

You need identical sticks of memory for it to work, and it needs to be
enabled in the motherboard BIOS. Make sure Performace Mode is set to
enabled.

Thanks very much. I've since done some looking around and think I understand
it better now.

Suppose I add two identical 512 Centon 3200s and put them in the blue slots
and use the performance mode. Presumably this will let them work in dual
channel mode.

Then--if I add in my non-identical 512 2700 Micron chips to the black slots,
giving me a total of 2gb, will this double mismatch between the two 2700
chips and between the 2700 and 3200 chips defeat my purpose?

Ken

 

[Sylvain VAN DER WALDE]

You need identical sticks of memory for it to work, and it needs to be
enabled in the motherboard BIOS. Make sure Performace Mode is set to
enabled.

Thanks very much. I've since done some looking around and think I understand
it better now.

Suppose I add two identical 512 Centon 3200s and put them in the blue slots
and use the performance mode. Presumably this will let them work in dual
channel mode.

Then--if I add in my non-identical 512 2700 Micron chips to the black slots,
giving me a total of 2gb, will this double mismatch between the two 2700
chips and between the 2700 and 3200 chips defeat my purpose?

Ken

Haven't you got a motherboard manual?

For DDR Ram only:

You must put one stick of Ram into 1 blue slot, and the other one in 1 black
(?) slot. Don't use both blue slots for a particular pair.

Sylvain.

 

[Sylvain VAN DER WALDE]

You need identical sticks of memory for it to work, and it needs to be
enabled in the motherboard BIOS. Make sure Performace Mode is set to
enabled.

Thanks very much. I've since done some looking around and think I understand
it better now.

Suppose I add two identical 512 Centon 3200s and put them in the blue slots
and use the performance mode. Presumably this will let them work in dual
channel mode.

Then--if I add in my non-identical 512 2700 Micron chips to the black slots,
giving me a total of 2gb, will this double mismatch between the two 2700
chips and between the 2700 and 3200 chips defeat my purpose?

Ken

Haven't you got a motherboard manual?

For DDR Ram only:

You must put one stick of Ram into 1 blue slot, and the other one in 1 black
(?) slot. Don't use both blue slots for a particular pair.

Addition: The blue and black slots work in pairs. For example: the first
blue slot in the row works with the first black slot in the row. And the
second blue slot works with the second black one.

It's best to look at the manual. I can't always be sure of my memory recall.

Sylvain.




Sylvain.

 

[KenV]

Haven't you got a motherboard manual?

For DDR Ram only:

You must put one stick of Ram into 1 blue slot, and the other one in 1
black (?) slot. Don't use both blue slots for a particular pair.

Indeed, I do have a MB manual and have practically worn out the memory
pages.

Nowhere in my manual does it say to put a pair of DDR sticks in unmatched
slots, i.e., one blue and one black.

It says:

"2. Use the blue DIMM slots first" on page 2-12

Under recommended memory configurations it either allows one of the blue or
one of the black slots to be populated by a single stick, or two blues or
two blacks, or both blues and both blacks, but never one black and one blue,
for 2 and 4 sticks respectively.

This is from the manual for the P4P800E-Deluxe. Am I reading it incorrectly?
If you have two non-identical sticks are you supposed to put one in the blue
slot and one in the black slot? If so, it deosn't say that anywhere that I
can see.

Ken

 

[Custom Computers]

When using identical sticks of memory for dual channel mode they need
to both be in the same color slot. When using two non-identical sticks
of memory it doesn't matter which slots there in since they won't work
in dual channel mode.

 

[KenV]

When using identical sticks of memory for dual channel mode they need
to both be in the same color slot. When using two non-identical sticks
of memory it doesn't matter which slots there in since they won't work
in dual channel mode.

OK--thanks again.

Ken

 

[Sylvain VAN DER WALDE]

Haven't you got a motherboard manual?

For DDR Ram only:

You must put one stick of Ram into 1 blue slot, and the other one in 1
black (?) slot. Don't use both blue slots for a particular pair.

Indeed, I do have a MB manual and have practically worn out the memory
pages.

Nowhere in my manual does it say to put a pair of DDR sticks in unmatched
slots, i.e., one blue and one black.

It says:

"2. Use the blue DIMM slots first" on page 2-12

Under recommended memory configurations it either allows one of the blue or
one of the black slots to be populated by a single stick, or two blues or
two blacks, or both blues and both blacks, but never one black and one blue,
for 2 and 4 sticks respectively.

This is from the manual for the P4P800E-Deluxe. Am I reading it incorrectly?
If you have two non-identical sticks are you supposed to put one in the blue
slot and one in the black slot? If so, it deosn't say that anywhere that I
can see.

Ken

Hello Ken.
I owe you an apology. I've just re-read the manual, and it seems that my
memory let me down.
Yes, the pair of identical sticks go into the blue slots, and the other pair
in the black slots. My board, P4C800-E de luxe, takes 4 GB of Ram, and not 2
Gb as stated by myself before.
I have to double check my _own_ configuration now.
Again, apologies.
P.S. Reading the manual _carefully_, should remove any doubts.

Sylvain.

 

[KenV]

Hello Ken.
I owe you an apology. I've just re-read the manual, and it seems that my
memory let me down.
Yes, the pair of identical sticks go into the blue slots, and the other
pair in the black slots. My board, P4C800-E de luxe, takes 4 GB of Ram,
and not 2 Gb as stated by myself before.
I have to double check my _own_ configuration now.
Again, apologies.
P.S. Reading the manual _carefully_, should remove any doubts.

Sylvain.

Hi Sylvain,

Thanks for your note. No problem.

As it is, the ASUS manuals are not the clearest in terms of the details, and
they don't always explain the alternatives well.

I called ASUS tech support today, just to see what they would advise. They
said that unless you are a serious gamer, or are using highly demanding
programs like video editing, that there probably wouldn't be a noticeable
performance improvement with dual as opposed to single channel, and that
adding memory to a 1GB system wouldn't enhance things much, either.

So--I am going to save some money and live with my two non-identical 512
chips. The system does run pretty well.

Ken

 

[Paul]

Thanks very much. I've since done some looking around and think I understand
it better now.

Suppose I add two identical 512 Centon 3200s and put them in the blue slots
and use the performance mode. Presumably this will let them work in dual
channel mode.

Then--if I add in my non-identical 512 2700 Micron chips to the black slots,
giving me a total of 2gb, will this double mismatch between the two 2700
chips and between the 2700 and 3200 chips defeat my purpose?

Ken

Dual channel works with pairs of matched modules. When using
four modules, they don't all have to match one another. But for
dual channel to work, there should be two matched pairs.

For example, these four sticks give a total of 3GB of memory
operating in a dual channel mode:

512MB <--> 512MB (first matched pair)
1GB <--> 1GB (second matched pair)

Now, consider what you can do to improve your two mismatched
sticks:

512MB single rank DIMM <--> 512MB single rank DIMM
512MB dual rank DIMM <--> 512MB dual rank DIMM

In the above case, you get a total of 2GB of RAM, and it
is operating in dual channel mode. But you should not
get "dynamic mode" operating, which is a way of interleaving
memory addresses. The rank mismatch in the above case, is
similar to the row/column mismatch in the first (3GB) test
case - things must be "very symmetric" for dynamic mode to
work (like 2 or 4 modules that match one another).

Dynamic mode gives a tiny improvement in performance,
and is not really worth worrying about. Dual channel, on
the other hand, could give you 10% application improvement,
for memory intensive applications. Most ordinary applications
like email/web surfing and the like, might not notice a
difference, but perhaps Photoshop may benefit from dual channel.

I did notice a detectable difference on a 865GE motherboard
built-in graphics, when using a dual channel memory
configuration - in fact, I detected that the memory modules
were mismatched, by the sluggish desktop performance I was
getting. Since you would be using a graphics card, that won't
be an issue on your board (865GE uses motherboard memory
for graphics memory requirements, which is why it mattered).

Intel has a document for the 865PE, which ranks the memory
performance according to which mode is being used. (It is
too bad they didn't provide benchmarks to quantify the
differences.) See the following, to learn more about how
dynamic mode works:

ftp://download.intel.com/design/chipsets/applnots/25303601.pdf

There are a few things I don't understand in that doc, such
as why the top two lines in the table in the back of the doc
are reversed. I thought as far as Intel was concerned, the
865PE doesn't have PAT (first cycle latency reduction when
DDR400 memory and FSB800 processor are run "sync"), so I don't
see what other factor has caused those two rows to be reversed.
The more ranks you use for dynamic mode, the better it is
supposed to work.

HTH,
Paul

 

[KenV]

Dual channel works with pairs of matched modules. When using
four modules, they don't all have to match one another. But for
dual channel to work, there should be two matched pairs.

For example, these four sticks give a total of 3GB of memory
operating in a dual channel mode:

512MB <--> 512MB (first matched pair)
1GB <--> 1GB (second matched pair)

Now, consider what you can do to improve your two mismatched
sticks:

512MB single rank DIMM <--> 512MB single rank DIMM
512MB dual rank DIMM <--> 512MB dual rank DIMM

In the above case, you get a total of 2GB of RAM, and it
is operating in dual channel mode. But you should not
get "dynamic mode" operating, which is a way of interleaving
memory addresses. The rank mismatch in the above case, is
similar to the row/column mismatch in the first (3GB) test
case - things must be "very symmetric" for dynamic mode to
work (like 2 or 4 modules that match one another).

Dynamic mode gives a tiny improvement in performance,
and is not really worth worrying about. Dual channel, on
the other hand, could give you 10% application improvement,
for memory intensive applications. Most ordinary applications
like email/web surfing and the like, might not notice a
difference, but perhaps Photoshop may benefit from dual channel.

I did notice a detectable difference on a 865GE motherboard
built-in graphics, when using a dual channel memory
configuration - in fact, I detected that the memory modules
were mismatched, by the sluggish desktop performance I was
getting. Since you would be using a graphics card, that won't
be an issue on your board (865GE uses motherboard memory
for graphics memory requirements, which is why it mattered).

Intel has a document for the 865PE, which ranks the memory
performance according to which mode is being used. (It is
too bad they didn't provide benchmarks to quantify the
differences.) See the following, to learn more about how
dynamic mode works:

ftp://download.intel.com/design/chipsets/applnots/25303601.pdf

There are a few things I don't understand in that doc, such
as why the top two lines in the table in the back of the doc
are reversed. I thought as far as Intel was concerned, the
865PE doesn't have PAT (first cycle latency reduction when
DDR400 memory and FSB800 processor are run "sync"), so I don't
see what other factor has caused those two rows to be reversed.
The more ranks you use for dynamic mode, the better it is
supposed to work.

HTH,
Paul

Paul,

Thanks very much. That is very helpful, as is the Intel document. I
appreciate the time you put into the detailed and clear explanation.

Ken

 

[DaveW]

You have to use IDENTICAL memory sticks to run in dual channel mode.