Windows XP does not recognize all extra memory installed

[Erik]

Hi,

I upgraded the memory of my computer from 512 Mb tot 1,5 Gb. I did this by
installing a 1 Gb stick in a free memory slot (so the other slot already
contained a 512 Mb memory stick).
The (windows-) program CPU-Z reports the correct amount memory installed -
so far no problem. However, the task manager of Windows XP Home reports only
982252 kb, so about 1 Gb.
Obviously the question is: why does Windows XP detect only 1 Gb?
Some more info:
- motherboard Asus P5RD2-VM
- CPU: intel pentium D915, socket 775 LGA
- memory is DDR2. Max bandwidth slot 1 (512 Mb stick) is 266 Mhz, max
bandwidth slot 2 (1 Gb stick) is 333 Mhz

Thanks in advance!

 

[ultraport]

Try putting the memmory in different colored slots.

 

[Loren Pechtel]

Hi,

I upgraded the memory of my computer from 512 Mb tot 1,5 Gb. I did this by
installing a 1 Gb stick in a free memory slot (so the other slot already
contained a 512 Mb memory stick).
The (windows-) program CPU-Z reports the correct amount memory installed -
so far no problem. However, the task manager of Windows XP Home reports only
982252 kb, so about 1 Gb.
Obviously the question is: why does Windows XP detect only 1 Gb?
Some more info:
- motherboard Asus P5RD2-VM
- CPU: intel pentium D915, socket 775 LGA
- memory is DDR2. Max bandwidth slot 1 (512 Mb stick) is 266 Mhz, max
bandwidth slot 2 (1 Gb stick) is 333 Mhz

Some boards won't like the mismatch and will only use 512mb off that
second stick.

And some really obnoxious boards won't even boot in that
configuration--mixing the 266 with the 333 doesn't always fly.

 

[Erik]

Thanks to all of you.

I found out the BIOS also reports 1 Gb memory, so it's not an os related
problem. Only the program CPU-Z detects the size of the sticks installed -
yet this is not the size available to the system.

Some boards won't like the mismatch and will only use 512mb off that
second stick.

I'm afraid that's the problem. I'll see if I can replace the 512 MB stick by
another 1 Gb stick of 333 Mhz (thus similar specs)

 

[Loren Pechtel]

Make sure that both sticks of ram are the exact same spec, or else you
will have problems all the way.

Not always. Some boards tolerate it, some don't. Some tolerate it
only if the slowest memory is in the first slot. (They take the
settings off the first stick rather than the slowest one.)

If the board tolerates the 512mb/1gb mismatch that slows it as they
can't be used in paired mode.

 

[Flasherly]

Hi,

I upgraded the memory of my computer from 512 Mb tot 1,5 Gb. I did this by
installing a 1 Gb stick in a free memory slot (so the other slot already
contained a 512 Mb memory stick).
The (windows-) program CPU-Z reports the correct amount memory installed -
so far no problem. However, the task manager of Windows XP Home reports only
982252 kb, so about 1 Gb.
Obviously the question is: why does Windows XP detect only 1 Gb?
Some more info:
- motherboard Asus P5RD2-VM
- CPU: intel pentium D915, socket 775 LGA
- memory is DDR2. Max bandwidth slot 1 (512 Mb stick) is 266 Mhz, max
bandwidth slot 2 (1 Gb stick) is 333 Mhz

That should be a good board. I've never personally run with an ASUS I
didn't like, just a Gigabyte. Do other programs - Everest and System
Explorer - report the same as CPU-Z? Maybe CPU-Z is using different
"hooks" than XP's into the system. Add those software diagnostics and
all four should report a true state when either memory module, but not
both, is installed;- if not, stop, you've got weirdness. Also swap
both physical modules in all available memory slots to verify the
inconsistent state you're reporting continues to hold true for the
programs. If not, and you get a valid memory count, take Prime95 and
begin assiduously to torture it while raising, initially from the
lowest, what if any memory speed specifications the BIOS allows.

 

[Flasherly]

I had this problem and after several hours of headaches found a
solution.
On restart, before the Windows splash screen appears, press F2. Arrow
down to "OS Install mode". Set this to "Off". (Before you do this,
press F1 for the help menu. It will explain what this switch does). If
the switch is On, the computer only recognizes 256m of RAM.

From Dell's support homepage for PowerEdge systems: "The OS Install
Mode option in the System Setup program is set to On. This limits the
amount of available memory to 256 MB because some operating systems
will not complete installation with more than 2 GB of system memory."

For someone doing that with mom&pop's VG motherboard -- very generic,
Made in Bathtub, subcategory Pacific Rim -- they'd know immediately to
pull out memory modules or turn them off in the BIOS. Never Attempt
Greater Than 2G XP Installs, like everything else about computers, is
just so logical.

I'd never thought, in a million years, Dell would so kind to actually
write their very own BIOS routines for that.