4 GB memory not recognised in XP Pro?

[Chuckles The Scary Clown]

Hi,

I've just upgraded my system to 4gb of DDR2 PC3200 memory (4 x 1gb sticks)
and Windows XP Pro is reporting only 3.25gb of RAM installed?

The memory checks out fine with Memtest+ diagnostic software so is there an
issue with XP and large amounts of memory?

Thanks in advance.

 

[Leythos]

Hi,

I've just upgraded my system to 4gb of DDR2 PC3200 memory (4 x 1gb sticks)
and Windows XP Pro is reporting only 3.25gb of RAM installed?

The memory checks out fine with Memtest+ diagnostic software so is there an
issue with XP and large amounts of memory?

Thanks in advance.

This link should explain it in enough details for you:
http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

 

[Guest]

I had the exact same problem with my computer but i was messing around in the
bios and was able to get it up to 3.8 gb that it showed. I lowered the memory
for the videocard in the bios and anything that you think might have to do
with some kind of memory change it on at a time to see if it increases. That
is what i did to get it up from 3.2 to 3.8. Because i have a 256 mb video
card in my computer and when i lowered it from 256 to 128 or maybe it was 64
in the bios the memory jumped to 3.8 mb or memory it showed

 

[Bob I]

Please read the "For example" section to undersand the cause for what
you see.

http://www-307.ibm.com/pc/support/site.wss/document.do?lndocid=MIGR-40247

 

[Guest]

I must confess -- this particular link sheds no real light on the problem.

I also have a WinXP Pro system (Dell Precision) with 4GB of physical RAM.
However, the OS is reporting only 3.00GB available. This is a far cry from
the usual customer site I visit, where it shows usually around 3.6GB of
memory available. The video card should be picking up just over 256MB at
most, so it would be hard to believe then even a video shadow would be
affecting this.

Is it possible that the OS is detecting a memory error in one of the four
1GB DIMMs and disabling it, without posting anything in the Event logs?

Dell tells me that the problem is a Microsoft problem, since the BIOS sees
4GB at boot time, and diagnostics pan out with no issues. Are there any
other suggestions?

 

[Maurice N ~ MVP]

Hi Bill,

I suggest you read some discussions on this topic from 2002. Following is a
link to an archived thread via Google.
<http://tinyurl.com/7cfou>


Unless you have other evidence (such as results from RAM memory tester), I'd
imagine your RAM is ok.
HTH

 

[» mrtee «]

/3GB
This switch forces x86-based systems to allocate 3 GB of virtual address
space to programs and 1 GB to the kernel and to executive components. A
program must be designed to take advantage of the additional memory address
space. With this switch, user mode programs can access 3 GB of memory
instead of the usual 2 GB that Windows allocates to user mode programs. The
switch moves the starting point of kernel memory to 3 GB. Some
configurations of Microsoft Exchange Server 2003 and Microsoft Windows
Server 2003 may require this switch.

For additional information, click the following article number to view the
article in the Microsoft Knowledge Base:
823440 You must use the /3GB switch when you install Exchange Server 2003 on
a Windows Server 2003-based system


For additional information, click the following article number to view the
article in the Microsoft Knowledge Base:
171793 Information on application use of 4GT RAM tuning

 

[Star Fleet Admiral Q]

Actually I've read it somewhere, don't know if it was MS or what, but on
some PC Motherboard/BIOS combinations where XP/Win2k3 SE are running with 4
1GB memory chips, not all of the 4GB is recognized - the OS would only see
anywhere from 3GB to 3.5GB - I myself can attest this is true for both, as I
do have the same as you, a Dell Precision 470 with 4 1GB 400Mhz DDR sticks,
and also I dual boot, between XP Pro SP2 and Win2k3 SE SP1 and both
recognize only 3.5GB. After discovering this fact, I put the half-gig
wasted to use by going into the BIOS and shadowing the Video card (256MB)
with dual DVI out connections (each with a NEC LCD 19" monitor) with 512MB
of memory. If windows can't see/use it, then I at least let the Video Card
shadow/buffer graphics acceleration with it.

--

Star Fleet Admiral Q @ your Service!

http://www.google.com
Google is your "Friend"