Installed additional 2GB of Memory but Windows does see all of it, why?

I had 2 GB of Ram that came with the computer and I added another 2 GB of Kingston memory yesterday. Windows only says I have 3.326 GB of memory. I ran the DXDIAG utility and it says 3.326 GB also. I thought one of the two memory stick I added was bad. When I add the first stick windows showed I have 3 GB, it doesn’t matter which of the 2 sticks I add first it says 3 GB. I have an Intel Dual Core 2.66 Ghz Processor that is running Windows XP Professional SP2. Do you think I have 4 GB of memory now and there is some glitch in Windows memory accuracy saying how much Ram I have or do I have an issue with one of the memory sticks?

That’s the way it is with XP so your RAM is fine.


You might have a look at these MSKB articles:

Also there should be a statement about this issue in your mainboard manual. Indeed, you have half a Gig of RAM lying around, that cannot be used at all.


That’s all windows xp will show or use. Have to go to vista to use anymore. I have exactly the same thing going on.

Actually, all 32-bit operating systems – Windows Vista 32-bit included – will have the same limitation of not being able to see all 4GB of memory. You will need a 64-bit operating system and 64-bit hardware in order to see all 4GB (or more).

Thanks for the comments! I will not return the memory.

I have same problem but it’s not really a problem as i’m just using 2 gigs for now and will keep them for rainy day.

This is an issue with all Windows 32-Bit Operating Systems, including Vista.
As mentioned above, only 64-BIT Operating Systems can access the full 4 GB of memory. This would require a 64-BIT CPU.

There are recommendations for solutions floating around that suggests that modifying the [B]boot.ini[/B] to activate the [B]Physical Address Extension[/B] mode would rectify the issue.

The /PAE boot.ini switch, on NT-descended Windows flavors, activates the Physical Address Extension mode that’s existed in every PC CPU since the Pentium Pro. That mode cranks the address space up to 64 gigabytes (two to the power of 36), and the computer can then give a 4Gb addressing block within that space - or even more, with extra tricks - to each of several applications.

For those who are interested, there is an extremely interesting article on this topic HERE

Daniel Rutter does a terrific job in simplifying the explanations.

I have 2 512 mb installed (1GB) If I buy 2 1GB and install them both will that be a problemor should I just get 2 more 512mb? Also whats a good brand?

Corsair, OCZ, just go to and search memory.:iagree:

Would you say there the best brands? Or are there more compatible brands?

Metrock, I have 2x 1GB and 2x 512Mb sticks in my PC without problems. One motherboard I have reports 3007MB and the other reports 3072MB (and causes vista loads of problems until its patched with the 3GB+ causes BSOD patch).

The main reason that PC’s have problems with 4GB of ram is that 32bit hardware can only address 4GB of ram, in that space there needs to be space available for the graphics card interface (it needs memory address space so that the CPU can write to its memory) and most adaptors need memory space so that the CPU can talk to them as well. This all takes space away from the 4GB limit.

Some motherboards allow the use of PAE extensions to re-map some of the overwritten memory above the 4GB space, this needs all 3 factors to support its use (motherboard BIOS, CPU and OS). You can try enabling PAE in windows but unless your motherboard BIOS supports it as well you wont get any advantage.

32 bit OS’ have a limit which depends on the hardware and BIOS used on the mobo, also within the OS…
Some PCI adresses are in the 3-4gb area so they cannot be used by the 32bit OS.