Dual Channel

  • Thread starter Thread starter Charlie
  • Start date Start date
Check the motherboard specifications. Also if you can remove the
PC case ( or side panel ) and check the RAM slot configuration. A
dual-channel RAM setup usually has 4 slots with a slight separation
between the 2nd & 3rd Slots. If RAM is installed in 1,3 or 2, 4 it's
likely the motherboard employs Dual-Channel. Some BIOS setups
will actually show configuration and type in use.
 
I downloaded and executed cpuz and the "memory" tab indicates single mode.
My MB (Asus P4P800-E) supports dual channel. I have 4 512 simms (400mhz
PC3200 low density) in each of the 4 slots. Would there be something
prohibiting it from running in dual channel mode?
 
Charlie said:
I downloaded and executed cpuz and the "memory" tab indicates single mode.
My MB (Asus P4P800-E) supports dual channel. I have 4 512 simms (400mhz
PC3200 low density) in each of the 4 slots. Would there be something
prohibiting it from running in dual channel mode?
Click to expand...

Your next step, is to examine the information in the
"SPD" tab for each stick.

512MB sticks come in two kinds. 512MB double sided, with
16 chips. 512MB single sided, with only eight chips,
all located on one side of the module.

If you put an eight chip module in the same color
slot as a sixteen chip module, the motherboard
could not "dual channel" those.

You can start by

1) Removing all DIMMs. Inspect the DIMMs, and select a pair
which appear visually similar. Install in the same
colored slots. Boot Windows and check CPUZ again.
Does it indicate dual channel now ?

2) Now, examine the remaining DIMMs ? Are they matched ?
Install them in the remaining (matched color) slots.
Boot the computer. Is it still dual channel ?

As an example of how it could be botched, you could have
three 16 chip modules, and one 8 chip module. Installing
two 16 chip modules, would report dual channel. But then
the installation of an unmatched second set, would ruin
it, and it would report virtual single channel mode.

The memory guide for 865 family is here.

ftp://download.intel.com/design/chipsets/applnots/253036.htm

Each generation of Intel chipsets have different capabilities.
Early dual channel ones, are "strict" dual channel. The modules
must match, to a high degree (rows, columns, banks, ranks, all
equal, in same colored slots).

The next level, asks that the user balance the total
memory on each channel. A user can use 2x512MB on one
channel, and a single 1GB DIMM on the other channel.
Select chipsets run that config, in dual channel.

The latest mode, is "Flex memory" mode. It doesn't
require much of anything, but to have some memory
on each channel. Say, for example, I install a
256MB stick on one channel, and a 1GB stick on the
other channel, of a Flex memory chipset board. Then
the lower (2x256MB) area runs in dual channel, and
the upper remaining 768MB of the 1GB stick runs
in single channel mode. Memory performance in that
case varies, depending on where data is stored within
available system memory.

As far as I can recollect, yours would be "strict".

Using this picture as a reference, and assuming you have
two different, matched pairs of RAM, it would go like this.

http://www.asus.com/999/images/products/178/178_l.jpg

blue 8 chip 512MB stick
black 16 chip 512MB stick

blue 8 chip 512MB stick
black 16 chip 512MB stick

Post back how it goes.

Paul
 
Thanks Paul for your help. All of my DIMMS look phisically the same. I
played around a bit after reading your response. My 2 original 512 DIMMs
were in slot 1 & 3 and were running dual mode. After adding my 2 new matched
512 DIMMs to slot 2 & 4 my machine would freeze and not boot. Removing the
original DIMMs from slot 1 &3 I replaced them with the two new DIMMs in slot
1 & 3 and left slots 2 & 4 empty. The machine would freeze and not boot.
Placing the new DIMMs in slot 1 &2 the machine would boot and run in single
mode. Finally I ended up with the original 2 DIMMs in slots 3&4 and the 2
new DIMMs in slots 1 & 2. The machine boots fine and recognizes the full 2
gig but is obviouslly running in single mode. The machine would not boot
with the new DIMMs in the dual mode slotts. I must have one of the older
"strict dual channel" MB.

My question is under the circustances is it better to run a machine with 2
gig of ram in single mode or 1 gig of ram in dual mode.
 
Charlie said:
Thanks Paul for your help. All of my DIMMS look phisically the same. I
played around a bit after reading your response. My 2 original 512 DIMMs
were in slot 1 & 3 and were running dual mode. After adding my 2 new matched
512 DIMMs to slot 2 & 4 my machine would freeze and not boot. Removing the
original DIMMs from slot 1 &3 I replaced them with the two new DIMMs in slot
1 & 3 and left slots 2 & 4 empty. The machine would freeze and not boot.
Placing the new DIMMs in slot 1 &2 the machine would boot and run in single
mode. Finally I ended up with the original 2 DIMMs in slots 3&4 and the 2
new DIMMs in slots 1 & 2. The machine boots fine and recognizes the full 2
gig but is obviouslly running in single mode. The machine would not boot
with the new DIMMs in the dual mode slotts. I must have one of the older
"strict dual channel" MB.

My question is under the circustances is it better to run a machine with 2
gig of ram in single mode or 1 gig of ram in dual mode.
Click to expand...

That depends on whether you needed the 2GB of RAM or not in the first place.

Use control-alt-delete to open the Task Manager.

Under Commit Charge, the Total is what you're using right now. The
Peak is the most you had busy during the day. My total currently
is 1072700, and my peak is 1167476. If I purchased 1GB of memory,
that would be 1048576, so I need slightly more than 1GB based on today's
usage pattern. On some days, my peak is 800000, so 1GB of RAM would be
sufficient.

I operated for a couple years with 1GB, doing basically the same
things I am doing now, so this isn't typically a problem for me.
When I last upgraded, I got a 2GB memory kit, and as you can see
at the moment, I'm barely using the second gig.

As for all the DIMMs being identical, if the machine is reporting
single channel at the moment, and all the DIMMs are double sided
and have a capacity of 512MB, then chances are they're identical
in terms of rows,columns,banks,ranks. The DIMMs may differ in
CAS or max speed (PC3200) or whatever, and the BIOS should be
able to select settings that are slow enough, so that all
DIMMs would work. In other words, you should be in dual channel
mode, based on what you've said so far.

If you go into CPUZ, use the "About" tab, there is a
"Register Dump" option in there. By default, it'll dump
to "cpuz.txt". For example, this is what is dumped for
one of my two DIMMs. This is for a DDR2 DIMM, but yours
are DDR DIMMs, so the voltage will be a higher value.
Try dumping the description of all four of your DIMMs.

*******
DIMM #1

General
Memory type DDR2
Module format Regular UDIMM
Manufacturer (ID) Kingston (7F98000000000000)
Size 1024 MBytes
Max bandwidth PC2-5300 (333 MHz)
Part number 99C5316-019.A00LF
Serial number 12345678
Manufacturing date Week 25/Year 08

Attributes
Number of banks 2
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP no
XMP no

Timings table
Frequency (MHz) 200 266 333
CAS# 3.0 4.0 5.0
RAS# to CAS# delay 3 4 5
RAS# Precharge 3 4 5
TRAS 9 12 15
TRC 12 16 20
*******

Paul
 
Thanks again Paul. I did a Register Dump as you suggested and the specs are
the same for all DIMMs. For some reason my MB just doesn't like my new DIMMs
in dual channel mode. Oh well.

By the way. Thanks for the tip on Task Manager about checking on maximum
memory usage. I have used Task Manager many times but never noticed that
section. It shows that I am barely into the second gig of memory when I am
doing my heaviest processing.

Thanks again for all the help.
 
Charlie said:
Thanks again Paul. I did a Register Dump as you suggested and the specs are
the same for all DIMMs. For some reason my MB just doesn't like my new DIMMs
in dual channel mode. Oh well.

By the way. Thanks for the tip on Task Manager about checking on maximum
memory usage. I have used Task Manager many times but never noticed that
section. It shows that I am barely into the second gig of memory when I am
doing my heaviest processing.

Thanks again for all the help.
Click to expand...

In terms of settings on P4P800-E Deluxe.

AI Overclock Tuner [Manual] <--- Doesn't do anything, but makes some other setting
options appear in the menu. I like to see what
the BIOS is doing.

Performance Mode [Standard] <--- To avoid overly aggressive automatic settings.

DDR Reference Voltage [2.75] <--- Most RAM can take this much voltage. JEDEC spec
says 2.6V +/- 0.1V for DDR400. So 2.75V should
not hurt anything. You can turn it down to 2.65V
if it will remain stable at that voltage. Check
the package the RAM came in, for a suggested
maximum voltage.

There is no Command Rate control on Intel boards, and presumably that function
is implicit in the design.

I don't really know of a reason for freezing, unless you've adjusted something
from the Auto settings that the board doesn't like.

I never use "Turbo" settings, because it turns out they need
CAS2 memory. Industry standard DDR memory would be CAS3 and
a bit slower than CAS2 (which means, lower latency). So Turbo
is only consistent with "Enthusiast" RAM. Using something like
Turbo, would cause problems.

The "Memory Acceleration Mode" might be applied if you have
a FSB800 processor and DDR400 RAM. My P4C800-E board has something
similar. Asus figured out how to get that mode from the 865, but
gave it a different name, so they wouldn't piss off Intel. It
involves a lower latency datapath to memory, when all the components
share synchronous clocks. You don't need to use this, as the optimization
is almost unnoticeable (you'd need a stopwatch to see it). You can
safely leave it in [Auto], since for many operating conditions in
the chipset, it is not an applicable mode.

If you want some test cases to run, try using one of the good sticks,
and move it from slot to slot, and test that all the slots on your
motherboard work. That will eliminate a bad slot as the cause.

Anyway, have fun.

Paul
 
Charlie said:
You can you tell if your computer is operating in dual channel mode?
Click to expand...

"You can you", not intelligible.

"can you" meaning the reader (me)?

My award bios tells me that immediately after the RAM count.
--
Dave

CDOs are how we got here.
A modified version, new taxes in the future, is how Congress will get us
out?
 
My question is under the circustances is it better to run a machine with 2
gig of ram in single mode or 1 gig of ram in dual mode.
Click to expand...


For the great majority of people, it would make no difference at all.

How much RAM you need for good performance is *not* a
one-size-fits-all situation. You get good performance if the amount of
RAM you have keeps you from using the page file, and that depends on
what apps you run. Most people running a typical range of business
applications find that somewhere around between 256MB and 512MB works
well, others need more. Almost anyone will see poor performance with
less than 256MB. Some people, particularly those doing things like
editing large photographic images, can see a performance boost by
adding even more than 512MB--sometimes much more.

If you are currently using the page file significantly, more memory
will decrease or eliminate that usage, and improve your performance.
If you are not using the page file significantly, more memory will do
nothing for you. Go to
http://billsway.com/notes_public/winxp_tweaks/ and download
WinXP-2K_Pagefile.zip and monitor your page file usage. That should
give you a good idea of whether more memory can help, and if so, how
much more.
 
You have really peaked my curiosity as to why my 2 new DIMMs will not
function in dual mode. The specs on all 4 DIMMs appear to be the same from
the log report with CAS delay of 3 and a voltage of 2.5. I check the BIOS
settings you referred to and AI Overclock Tuner is set to [Manual] and the
Performance Mode was set to [Auto]. I changed this setting to [Standard] and
rebooted with only the 2 new DIMMs in slots 1 & 3. The machine begins to
boot and starts to load the OS (Windows XP Pro) when the BSOD flashes for a
split second and then it starts the reboot process all over again. There
were no issues listed in the Event Viewer of Windows.

This really isn't a major problem in the scheme of things but sometimes I
just can't let go until I find the answer. I guess it kind of becomes a
game. Thanks again for all your recommendations and help.

Paul said:
Charlie said:
Thanks again Paul. I did a Register Dump as you suggested and the specs
are the same for all DIMMs. For some reason my MB just doesn't like my
new DIMMs in dual channel mode. Oh well.

By the way. Thanks for the tip on Task Manager about checking on maximum
memory usage. I have used Task Manager many times but never noticed that
section. It shows that I am barely into the second gig of memory when I
am doing my heaviest processing.

Thanks again for all the help.
Click to expand...

In terms of settings on P4P800-E Deluxe.

AI Overclock Tuner [Manual] <--- Doesn't do anything, but makes some
other setting
options appear in the menu. I like to
see what
the BIOS is doing.

Performance Mode [Standard] <--- To avoid overly aggressive automatic
settings.

DDR Reference Voltage [2.75] <--- Most RAM can take this much voltage.
JEDEC spec
says 2.6V +/- 0.1V for DDR400. So 2.75V
should
not hurt anything. You can turn it down
to 2.65V
if it will remain stable at that
voltage. Check
the package the RAM came in, for a
suggested
maximum voltage.

There is no Command Rate control on Intel boards, and presumably that
function
is implicit in the design.

I don't really know of a reason for freezing, unless you've adjusted
something
from the Auto settings that the board doesn't like.

I never use "Turbo" settings, because it turns out they need
CAS2 memory. Industry standard DDR memory would be CAS3 and
a bit slower than CAS2 (which means, lower latency). So Turbo
is only consistent with "Enthusiast" RAM. Using something like
Turbo, would cause problems.

The "Memory Acceleration Mode" might be applied if you have
a FSB800 processor and DDR400 RAM. My P4C800-E board has something
similar. Asus figured out how to get that mode from the 865, but
gave it a different name, so they wouldn't piss off Intel. It
involves a lower latency datapath to memory, when all the components
share synchronous clocks. You don't need to use this, as the optimization
is almost unnoticeable (you'd need a stopwatch to see it). You can
safely leave it in [Auto], since for many operating conditions in
the chipset, it is not an applicable mode.

If you want some test cases to run, try using one of the good sticks,
and move it from slot to slot, and test that all the slots on your
motherboard work. That will eliminate a bad slot as the cause.

Anyway, have fun.

Paul
Click to expand...
 
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