Windows XP does not see 2G of RAM

[Brian R]

I have a Rack Mount PC with a Rocky 4786EVG-R30 Computer board that is used
for a test station. This PC came from the vendor (Industral PC) with 512MB of
RAM (one memory stick). Working with the vendor, I upgraded to 2G of RAM by
removing the 512MB stick and replacing it with two 1G sticks. Upon reboot,
BIOS correctly reports that I have 2G of RAM but:
Windows System Properies reports 480M
Task Manager reports 491M of Physical memory on the Performance task (same
value that I got when I had only 512M installed).
When I run: Start|Help and Support| Search on "ram", click on Get
Information about your computer, then click on View General Information about
this computer, the results lists 2G of ram.
Running winver from a command prompt give me a dialog box that indicates
"Physcial Memory available to windws: 491M".
Any idea why the hardware knows I have 2G but Windows XP doesn't?

 

[Paul]

I have a Rack Mount PC with a Rocky 4786EVG-R30 Computer board that is used
for a test station. This PC came from the vendor (Industral PC) with 512MB of
RAM (one memory stick). Working with the vendor, I upgraded to 2G of RAM by
removing the 512MB stick and replacing it with two 1G sticks. Upon reboot,
BIOS correctly reports that I have 2G of RAM but:
Windows System Properies reports 480M
Task Manager reports 491M of Physical memory on the Performance task (same
value that I got when I had only 512M installed).
When I run: Start|Help and Support| Search on "ram", click on Get
Information about your computer, then click on View General Information about
this computer, the results lists 2G of ram.
Running winver from a command prompt give me a dialog box that indicates
"Physcial Memory available to windws: 491M".
Any idea why the hardware knows I have 2G but Windows XP doesn't?

http://technet.microsoft.com/en-us/sysinternals/bb963892.aspx

/MAXMEM=

I keep a Knoppix and a Ubuntu CD handy, and boot a computer with that,
to compare the characteristics of hardware as seen by the different
operating systems. I'd pop one of those two in, and see if more memory
was reported. That would imply a forced limitation in the other OS.

To read the SPD info from the memory sticks in Windows, you can use CPUZ.
That doesn't have any special significance, except to be able to
see that each stick is still visible. (Note - it takes about 30 seconds
for the program to start, as it probes the SMBUS, and the SMBUS runs
at 10KHz or so.)

http://www.cpuid.com/cpuz.php

In the "About" tab, there is a "Registers" dump. The report there,
will actually include the entire table (in hex) contained inside the
SPD chip. You can download JEDEC standards for the SPD format, and
decode the contents by hand. That is useful in cases, where the
memory is not being detected properly. Occasionally, a DIMM is sold,
where the declaration in the SPD, does not match the chips on the
module.

Just a guess,
Paul

 

[JS]

I had a similar problem with a Dual Channel motherboard, it would
incorrectly report the amount of memory.
In my case the problem was a mismatch in specifications for the two memory
sticks.

JS

 

[Brian R]

Paul - Thank You!!!
I found /MAXMEM = 480 in the boot.ini file. When I remove this switch,
Windows XP sees all 2G of memory. I believe this switch was added by the
Matrox Meteor II frame grabber I use in this test station becasue when I
remove the MAXMEM switch, the frame grabber no longer works. I have contacted
Matrox to get more info.
Thanks again!
Brian R