Why less than 3 GB RAM recommendation in A8N31-SLI deluxe

Does anyone know why ASUS recommends using 3 GB or less RAM in the
A8N-32 SLI Deluxe when running Windows XP 32-bit version?


I guess my real question is, what happens if I install 4 GB of RAM? I
can see that Windows doesn't recognize it but will it create problems or
instability?

Thanks,

Bill

The largest generally available RAM sticks are 1 GB each. When you populate
all four RAM slots in current motherboards, memory timing errors become a
big problem. (It's a design problem that no one has overcome yet on consumer
boards.) So you need to limit yourself to (3) 1 GB sticks.

--
--------
DaveW
"Bill Jemison" wrote in message
...
Does anyone know why ASUS recommends using 3 GB or less RAM in the A8N-32
SLI Deluxe when running Windows XP 32-bit version?


I guess my real question is, what happens if I install 4 GB of RAM? I can
see that Windows doesn't recognize it but will it create problems or
instability?

Thanks,

Bill

Bill Jemison wrote:
Does anyone know why ASUS recommends using 3 GB or less RAM in the
A8N-32 SLI Deluxe when running Windows XP 32-bit version?


I guess my real question is, what happens if I install 4 GB of RAM? I
can see that Windows doesn't recognize it but will it create problems
or instability?


No 32-bit Microsoft OS will "see" much more than 3GB RAM. Having 4GB or more
should not present a problem.

"Bill Jemison" wrote in message
...
Does anyone know why ASUS recommends using 3 GB or less RAM in the
A8N-32 SLI Deluxe when running Windows XP 32-bit version?


I guess my real question is, what happens if I install 4 GB of RAM? I
can see that Windows doesn't recognize it but will it create problems or
instability?
You won't 'see' all 4GB.
The most you will see, will be between about 3.3GB, and 3.5GB.
The problem, is that unless you are running 'physical address extensions',
the processor can only address 4GB. Now out of that 4GB 'space', there are
a number of huge lumps used for other things. The video card BIOS,
motherboard BIOS, address range for the VGA, address ranges for cards like
network adapters, etc. etc.. How much is seen, depends on the cards
fitted. Now XP _server_ supports PAE. XP home, and Pro, have it enabled,
but without the option to address more than 4GB. W2K, supports it. There
is a downside to the larger allocation, in that several system tables hve
to grow in size, to handle the lager address range, which tends to 'undo'
the gain for memory sizes close to 4GB.
The physical memory 'handing' here, is a separate 'issue', to how XP, then
allocates memory to application/system tasks. By default, the maximum that
will be allocated to a single user task, is 2GB, with the remainder of the
space reserved for the system. There is a boot.ini switch (/3GB), which
alters this.
So installing 4GB, is perfectly possible, but about 2/3 of the last GB,
will be 'wasted', when using the standard versions of XP.

Best Wishes

On Sat, 17 Feb 2007 16:24:12 -0800, "DaveW" wrote:

The largest generally available RAM sticks are 1 GB each. When you populate
all four RAM slots in current motherboards, memory timing errors become a
big problem. (It's a design problem that no one has overcome yet on consumer
boards.) So you need to limit yourself to (3) 1 GB sticks.


Nope. Not 3. Either 2 or 4. The memory-controller is dual-channel, and
you will lose significant memory performance on the last Gbyte.

The only problem with running 4 sticks of 1GB, besides the software
limitations is that the command rate has to be set to 2T to compensate
for the extra capacitive bus-loading on the CPU. With 2 sticks of
high-quality 1Gbyte, the command rate can usually be set to 1T. And if
you are trying to push overclock, 2x1Gbyte is preferred anyway.

John Lewis

--
--------
DaveW
"Bill Jemison" wrote in message
...
Does anyone know why ASUS recommends using 3 GB or less RAM in the A8N-32
SLI Deluxe when running Windows XP 32-bit version?


I guess my real question is, what happens if I install 4 GB of RAM? I can
see that Windows doesn't recognize it but will it create problems or
instability?

Thanks,

Bill

DaveW.

Thanks for the response. Out of curiousity, how do memory timing errors
manifest themselves?

Bill

DaveW wrote:
The largest generally available RAM sticks are 1 GB each. When you populate
all four RAM slots in current motherboards, memory timing errors become a
big problem. (It's a design problem that no one has overcome yet on consumer
boards.) So you need to limit yourself to (3) 1 GB sticks.

Huh? I'm puzzled over your statement about the timing errors if you use four
ram slots. My P4C800-E Deluxe ran just fine with all slots populated as
follows 2x 512, 2x 256. I grant you this is 1.5 gig but it does have all
slots populated and is contrary to your statement....

"Bill Jemison" wrote in message
...
DaveW.

Thanks for the response. Out of curiousity, how do memory timing errors
manifest themselves?

Bill

DaveW wrote:
The largest generally available RAM sticks are 1 GB each. When you
populate all four RAM slots in current motherboards, memory timing errors
become a big problem. (It's a design problem that no one has overcome yet
on consumer boards.) So you need to limit yourself to (3) 1 GB sticks.

"JamesH" wrote in message

DaveW wrote:
The largest generally available RAM sticks are 1 GB each. When you
populate all four RAM slots in current motherboards, memory timing
errors become a big problem. (It's a design problem that no one has
overcome yet on consumer boards.) So you need to limit yourself to
(3) 1 GB sticks.

Huh? I'm puzzled over your statement about the timing errors if you
use four ram slots. My P4C800-E Deluxe ran just fine with all slots
populated as follows 2x 512, 2x 256. I grant you this is 1.5 gig but
it does have all slots populated and is contrary to your statement....

That's because his statement is nonsense.

The AMD K8 spec does say that when all 4 RAM slots are populated the memory
clock should drop from DDR400 to DDR333, which most BIOSs do these days if
they're set to autodetect. Ironically, improvements in the AMD 939 memory
controller mean it's no longer an issue. I have a 939 X2 4200 Manchester
E4. The E4 means it's one of the last 939 steppings and includes the
improved memory controller; only the E6 is later and the differences can be
measured by a bee's dick. I run 2 x Corsair TWINX1024-3200C2 (which means 4
x 512MB DDR400) at 2-3-3-6-2T @2.7v and at stock speeds (DDR400) it's just
fine. It will even overclock some, but not by as big a factor as the CPU,
but that takes us into an entirely different arena. I mention it only to
point out that I didn't start getting memory errors out of my 4 sticks until
I was overclocking the memory by more than 10% (IOW, at DDR440 or so it
started getting a bit flaky; I took it as far as DDR480 but then it
definitely had Issues).

Roger Hamlett correctly pointed out the real reason is a restriction in XP
that means part or even most of the 4th gig won't be available to
XP/applications as it's mapped to various devices instead. However, it
could still be worthwhile having if only to run all your memory in
dual-channel mode. Just how important that is is arguable according to need
and circumstance but it's still a legitimate factor to consider.

I really appreciate the comments. In case you all are interested, I used
4 gb for a couple of weeks and didn't experience any problem. During a
startup, I looked at some of the system info and realized the computer
was only recognizing about 2-1/4 gb. Because it was so low, I pulled 2
gb of memory and put in my one of my kid's desktops.

Thanks again for the comments and assistance.

Bill

DRS wrote:
"JamesH" wrote in message

DaveW wrote:
The largest generally available RAM sticks are 1 GB each. When you
populate all four RAM slots in current motherboards, memory timing
errors become a big problem. (It's a design problem that no one has
overcome yet on consumer boards.) So you need to limit yourself to
(3) 1 GB sticks.

Huh? I'm puzzled over your statement about the timing errors if you
use four ram slots. My P4C800-E Deluxe ran just fine with all slots
populated as follows 2x 512, 2x 256. I grant you this is 1.5 gig but
it does have all slots populated and is contrary to your statement....

That's because his statement is nonsense.

The AMD K8 spec does say that when all 4 RAM slots are populated the memory
clock should drop from DDR400 to DDR333, which most BIOSs do these days if
they're set to autodetect. Ironically, improvements in the AMD 939 memory
controller mean it's no longer an issue. I have a 939 X2 4200 Manchester
E4. The E4 means it's one of the last 939 steppings and includes the
improved memory controller; only the E6 is later and the differences can be
measured by a bee's dick. I run 2 x Corsair TWINX1024-3200C2 (which means 4
x 512MB DDR400) at 2-3-3-6-2T @2.7v and at stock speeds (DDR400) it's just
fine. It will even overclock some, but not by as big a factor as the CPU,
but that takes us into an entirely different arena. I mention it only to
point out that I didn't start getting memory errors out of my 4 sticks until
I was overclocking the memory by more than 10% (IOW, at DDR440 or so it
started getting a bit flaky; I took it as far as DDR480 but then it
definitely had Issues).

Roger Hamlett correctly pointed out the real reason is a restriction in XP
that means part or even most of the 4th gig won't be available to
XP/applications as it's mapped to various devices instead. However, it
could still be worthwhile having if only to run all your memory in
dual-channel mode. Just how important that is is arguable according to need
and circumstance but it's still a legitimate factor to consider.