Windows XP recognizes just 256MB out of the 1.2GB of RAM

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zoobooboozoo

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Hello there, i just switched the broken HDD on an old PC with another one, formatted and installed Windows XP SP3 on it.
The motherboard on the PC - nForce 3 250GB.

When I got to 'My Computer'-->'Properties' it says 1.81 GHz 256MB of RAM, while there are 1.2GB of RAM.

I checked my hardware using CPU-Z, and what I got is what I really have inside the PC:
2 X 512MB
1 X 256 MB
and a total of 1.2GB

the specifications of the three cards is the same, all PC3200(200MHz), and the only difference between them is the CAS Latency which is 2.5 on the 256MB card and 3 on the two 512MBs.



Anyone knows what might be wrong?
 
Use msconfig to see if the "MAXMEM=" setting (on the BOOT.INI tab under "advanced settings") has been enabled or explicitly set to 256MB.

Also check and make sure each stick is seated properly.
 
Here are some possible reasons why:

1) Both the 256MB stick and the two 512MB sticks are double-sided (double-ranked). The Athlon 64 was one of the first CPUs with an integrated memory controller (IMC) ever released. Previously, memory controllers were located on the motherboard rather than on the CPU die. IMCs often don't play nice with mixed ICs or ICs of mixed densities. Plus, newer systems often do not support the use of memory modules made with ICs of low desnity (do not confuse "ICs of low density" with "low-density memory"; the latter are simply modules with fewer than eight ICs per rank - and modern systems support such low-density memory modules only if those modules are single-ranked). In this case, the 256MB module has 128 Mbit ICs (meaning ICs with 128 Mbit total density each), while the two 512MB modules use 256 Mbit ICs. DDR1 systems manufactured since the advent of the Athlon 64 required that the total IC density per IC be at least 256 Mbits, while current DDR3 systems generally need a total density per IC of 1 Gbits.

2) The slots with the two 512MB modules in them could have been failing or dusty.
 
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Take out the 256MB stick and see if the computer boots off the 512s. If it does then you have mismatched RAM. If it doesn't try booting the 512s one stick at a time and see if you have a bad stick that is taking a channel offline. I recently had this problem with my RAM. One stick died and would still be recognized by the BIOS however was unuseable. If I tried to boot from just that stick the computer wouldn't boot.
 
C7J0yc3 said:
Take out the 256MB stick and see if the computer boots off the 512s. If it does then you have mismatched RAM. If it doesn't try booting the 512s one stick at a time and see if you have a bad stick that is taking a channel offline. I recently had this problem with my RAM. One stick died and would still be recognized by the BIOS however was unuseable. If I tried to boot from just that stick the computer wouldn't boot.
Click to expand...

A bad memory slot is also a possibility. The nForce 3 250 chipset is associated with the Socket 754 platform, whose IMC is single-channel only.
 
Do you have a video card? If I remember correctly most Windows versions will reserve an amount of RAM equal to the total video memory on a video card as a caching area. If you have a 1GB video card that could be a culprit.
 
Tytalus said:
Do you have a video card? If I remember correctly most Windows versions will reserve an amount of RAM equal to the total video memory on a video card as a caching area. If you have a 1GB video card that could be a culprit.
Click to expand...

Not for most dedicated cards. Onboard, or some that claim to have 1GB of RAM but actually use only 256 then steal the rest from the system would cause this issue, but if you had one of those, you would know.
 
What does bios say about it? Make sure you don't have an os install mode setting in your bios
 
You're not going to see a big boost over 1GB with XP anyways. Going from 256-512 then 512-1024 nets big gains but over 1GB is probably not worth the hassle unless you can buy new ram.
 
pallesen said:
What does bios say about it? Make sure you don't have an os install mode setting in your bios
Click to expand...

Thank you for a simple fix to what seemed like a big issue. I checked the bios and it WAS in OS Install Mode!! You saved me from another couple of hours researching this issue.
I am refurbishing an older Dell Dimension 1100, and installed a refurbished 160 GB hard drive. After installing the "new" hard drive it would only see 256 mb of memory and I know there was 1.2 GB installed. I am waiting for new sticks in the mail and I am upgrading to 2 GB of RAM.
 
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