Memory Problem

I have a P 4 3.0 Ghz. system on which I want to increase my memory. Currently that system is running smoothly with a Corsair DDR 2 1GB 667 Bus Speed Memory stick combined with a Twin MOS 256 MB DDR 2 stick. Giving the system a total memory of 1.12 GB. However, now when I try to run a Kingston 2 GB DDR 2 667 Memory stick with the Corsair one, what the system does is that it only detects the Kingston memory and gives me a total of 2GB memory instead of 3 GB. In the BIOS the slot with the Corsair memory stick gives a "Not Installed" message. I have tried all possible combinations of switching around the slots and also checked the two sticks individually. They both work perfectly when run individually.

Any suggestions on what the problem is? All help will be greatly appreciated.

Why not sell old memory modules and get new ones, with same brand. And if possible get exact same modules models.

If you are using a Win 32bit version, then RAM won't exceed more than 2GB. Read Post on Windows 32bit vs 64Bit.

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If you are using a Win 32bit version, then RAM won’t exceed more than 2GB. Read Post on Windows 32bit vs 64Bit.
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no! 32bit supports up to 4GB TOTAL system memory (including gfx RAM)…so that’s not a limitation.

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You are misinformed. Try adding 4GB in your Windows XP 32-bit Operating System and then check in your System Information or Task Manager and look yourself that how much memory (out of 4GB) is available to your Windows and other softwares?

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Oh man…please brush up your reading skills. i clearly stated “32bit supports up to 4GB TOTAL system memory (including gfx RAM)

meaning when the system info shows less than 4GB RAM, it’s because your Graphics Card memory is taking up some of the addressable memory, i.e. if you have 512mb gfx card and 4GB ram, your sys info will show 3.5GB ram.

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In the absence of the /PAE switch, the Windows memory manager is limited to a 4 GB physical address space. Most of that address space is filled with RAM, but not all of it. Memory-mapped devices (such as your video card) will use some of that physical address space, as will the BIOS ROMs. After all the non-memory devices have had their say, there will be less than 4GB of address space available for RAM below the 4GB physical address boundary.

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