Newly installed SDRAM is only partially showing up.

  • Thread starter Thread starter Damon
  • Start date Start date
D

Damon

Hi,

I just added two 1-GB sticks of SDRAM into my Dell computer to bring 2.5 GB
up to 4 GB, but it's only showing up under System as 3.25. Which is
interesting.

My tower has four RAM slots. When I bought the computer it had four 256 MB
sticks, two of which I replaced with two 1 GB sticks a while back (2.5) and
today I replaced the remaining two 256 MB sticks with two 1 GB sticks to
bring it up to 4 GB.

When I turned my computer back on, I was notified that my computer's memory
had changed, giving me the choice to continue or enter setup. I chose
"continue".

Everything seems to be running smoothly but it only shows up as 3.25 GB in
System. Is this because I accidentally skipped setup when prompted? Did I
perhaps install wrong? I am aware that RAM but be installed in a certain way
and as far as I can tell I made no mistakes. 3.25 is a strange number.

Any advice?

My specs:

Dell Dimension E510, Pentium 4 3.0 ghz, Windows XP Professional, and I
bought the new RAM off of the Dell website as per my system specs, don't know
the precise name. Any help would be appreciated.
 
Damon said:
Hi,

I just added two 1-GB sticks of SDRAM into my Dell computer to bring 2.5 GB
up to 4 GB, but it's only showing up under System as 3.25. Which is
interesting.

My tower has four RAM slots. When I bought the computer it had four 256 MB
sticks, two of which I replaced with two 1 GB sticks a while back (2.5) and
today I replaced the remaining two 256 MB sticks with two 1 GB sticks to
bring it up to 4 GB.

When I turned my computer back on, I was notified that my computer's memory
had changed, giving me the choice to continue or enter setup. I chose
"continue".

Everything seems to be running smoothly but it only shows up as 3.25 GB in
System. Is this because I accidentally skipped setup when prompted? Did I
perhaps install wrong? I am aware that RAM but be installed in a certain way
and as far as I can tell I made no mistakes. 3.25 is a strange number.
Click to expand...


This is an Address Space problem common to all 32-bit Windows client
operating systems, what Windows XP 32-bit will see depends on what
hardware you have in the computer, for most computers it ranges
anywheres between 2.75 to 3.5GB. Here is the reason why 32-bit XP
cannot fully use 4GB of RAM:

The problem that you are seeing is based on an older architecture
design for memory addressing. All the systems architecture up to this
point were based on a maximum of 4GB of total memory. Nobody really
thought, when this standard was designed, that this amount of memory
would actually be in use. The problem that has happened is that you
have PCI devices that require memory address ranges so that they can
properly execute their commands. These address ranges were mapped in
the upper sections of this maximum amount. Since nobody thought you
would be using up to 4GB these address ranges started around the last
500MB of the memory ranges. This range is called the T.O.M. or Top of
Memory range. This is the point in the bios where it places on hold the
amount of memory that is required by the various PCI devices that are
found on the motherboard. Thus when you have PCI cards or AGP cards
installed on your motherboard these devices hold on to memory for their
own use and take away from the maximum amount of memory that is
available for other tasks. This amount of memory can vary from a little
as 200MB all the way to 1GB of memory (or even more in select cases).
It just depends on the PCI devices you have and the amount of PCI
(including AGP) that you have installed all at once.

There is really no way to get around this basic design limitation. The
only way to get around these type of issues is to use certain new
designs that have brand new architectures (i.e 64-bit designs) that
allow memory to be mapped in area's above 4GB. The brand new Intel Xeon
designs and the AMD Opteron designs are built around 64-bit technology.
This is only ý of the equation that you would need to find success.
You would also need to use an OS that is actually PAE or PAE aware so
that it is able to address memory above the 4GB level. To find out
about PAE you can search Microsofts website for PAE (Physical Address
Extensions) and it will explain this concept and what OS's actually are
capable of providing this benefit. Windows 2000 and Windows 2003 would
fit both of these criteria. Windows XP on the hand would not allow this
type of ability.

Microsoft has addressed this type of issue in the following Microsoft
Article (291988)
http://support.microsoft.com/default.aspx?scid=kb;en-us;291988

[end quote]

http://www.tyan.com/archive/support/html/memory_faq.html

To be able to use the full 4GB RAM you have to use a 64-bit operating
system or a 32-bit operating system that is fully PAE aware.

John
Click to expand...
 
John said:
Damon said:
Hi,

I just added two 1-GB sticks of SDRAM into my Dell computer to bring
2.5 GB up to 4 GB, but it's only showing up under System as 3.25.
Which is interesting.

My tower has four RAM slots. When I bought the computer it had four
256 MB sticks, two of which I replaced with two 1 GB sticks a while
back (2.5) and today I replaced the remaining two 256 MB sticks with
two 1 GB sticks to bring it up to 4 GB.

When I turned my computer back on, I was notified that my computer's
memory had changed, giving me the choice to continue or enter setup.
I chose "continue".

Everything seems to be running smoothly but it only shows up as 3.25
GB in System. Is this because I accidentally skipped setup when
prompted? Did I perhaps install wrong? I am aware that RAM but be
installed in a certain way and as far as I can tell I made no
mistakes. 3.25 is a strange number.
Click to expand...


This is an Address Space problem common to all 32-bit Windows client
operating systems, what Windows XP 32-bit will see depends on what
hardware you have in the computer, for most computers it ranges
anywheres between 2.75 to 3.5GB. Here is the reason why 32-bit XP
cannot fully use 4GB of RAM:

The problem that you are seeing is based on an older architecture
design for memory addressing. All the systems architecture up to this
point were based on a maximum of 4GB of total memory. Nobody really
thought, when this standard was designed, that this amount of memory
would actually be in use. The problem that has happened is that you
have PCI devices that require memory address ranges so that they can
properly execute their commands. These address ranges were mapped in
the upper sections of this maximum amount. Since nobody thought you
would be using up to 4GB these address ranges started around the last
500MB of the memory ranges. This range is called the T.O.M. or Top of
Memory range. This is the point in the bios where it places on hold
the amount of memory that is required by the various PCI devices that
are found on the motherboard. Thus when you have PCI cards or AGP
cards installed on your motherboard these devices hold on to memory
for their own use and take away from the maximum amount of memory
that is available for other tasks. This amount of memory can vary
from a little as 200MB all the way to 1GB of memory (or even more in
select cases). It just depends on the PCI devices you have and the
amount of PCI (including AGP) that you have installed all at once.

There is really no way to get around this basic design limitation.
The only way to get around these type of issues is to use certain new
designs that have brand new architectures (i.e 64-bit designs) that
allow memory to be mapped in area's above 4GB. The brand new Intel
Xeon designs and the AMD Opteron designs are built around 64-bit
technology. This is only ý of the equation that you would need to
find success.
You would also need to use an OS that is actually PAE or PAE aware so
that it is able to address memory above the 4GB level. To find out
about PAE you can search Microsofts website for PAE (Physical Address
Extensions) and it will explain this concept and what OS's actually
are capable of providing this benefit. Windows 2000 and Windows 2003
would fit both of these criteria. Windows XP on the hand would not
allow this type of ability.

Microsoft has addressed this type of issue in the following Microsoft
Article (291988)
http://support.microsoft.com/default.aspx?scid=kb;en-us;291988

[end quote]

http://www.tyan.com/archive/support/html/memory_faq.html

To be able to use the full 4GB RAM you have to use a 64-bit operating
system or a 32-bit operating system that is fully PAE aware.

John
Click to expand...
Thanks for the great explanation.
Buffalo
Click to expand...
 
Hi,

I just added two 1-GB sticks of SDRAM into my Dell computer to bring 2.5 GB
up to 4 GB, but it's only showing up under System as 3.25. Which is
interesting.
Click to expand...


All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.


But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.


Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.
 
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