I have 3gb RAM, but XP only showing 2Gb?

[mikrev007]

A software designer from Microsoft writes a few words about it here: http://www.gamasutra.com/view/feature/3602/sponsored_feature_ram_vram_and_.php?page=3

 

[Scotteq]

By way of Clarification on what's what: Data is duplicated between the respective memory allocated to each card in a CF/SLI setup. This is different from the portion mapped to the address table, which is used for I/O purposes.



BTW - There's a lot of good information being exchanged in this thread - Thank Yo to all participants.,

 

[GX5000]

XPS 720 H2C

Dual Boot
XP SP2 32bit
Vista 32bit

Two Nvidia 8800 Ultra

Original configuration has 4gb 4x1GB modules Corsair Dominator. 2.5GB show available on both OS's. I guess the memory for the Nvidia cards Is what makes it 2.5GB

I was going to install XP 64bit to be able to use more ram for some 3D software that need it. I installed 8GB 4x2GB before installing the 64bit OS.

Both the above two 32bit OS's read only 2GB now.

Does anyone know why?

 

[rags_20]

Maybe your motherboard does not support 2GB modules?

 

[GX5000]

Maybe your motherboard does not support 2GB modules?

The motherboard supports up to 8GB.

If I only use one pair of the 2gb modules 2x2gb it reads like it did with the 4 x 1gb modules.

 

[0ffl1n3]

I have the same issue as the OP, 2gig upgrade to 3gig and only 2.25gig showing in Windows XP pro and Fedora Core 9 x86_64.

So definitely NOT a software issue. I was puzzled as I purposely bought only enough RAM for 3gig knowing 4gig would only give me a bit over 3 anyway.

So after switching the ram every which way and no different results, I decided to pull the graphics card (nVidia 512meg), and put in an old ATi 128meg card to see if there was any difference....

after that the full 3.0gig shows up in XP and linux... so basically WTF?? Thought maybe the BIOS needed the memory installed first, then graphics card, so put the 512mb back in but then back down to 2.25gig...

basically I have no idea how a 512meg graphics card is eating 750meg of memory out of the 3gig total? (n.b. I do NOT mean 4g)

One idea I had is that since the theoretical max limit for 32bit systems is 3.25gig (even with 4gig installed) that maybe somehow it's eating 2 x 512mb out of 3.25gig for the graphics card is it because it's dual head?... weird, almost be tempted to try another brand graphics card to see what happens, but that's an expensive test for little to no gain and my old 128meg does not support my monitor's native res....

 

[diznanl]

You're lucky you can see as much RAM as you can. I'm running XP 32, have 4 gigs of RAM, but can only see 2.5 of them. I'm assuming this is due to the 768mb of my 8800gtx card. What else would it be?

 

[0ffl1n3]

It is a fault with BIOS or nVidia's memory addressing...

I assume it is because the older BIOSes were designed thinking that people would never afford or need more than 2gig memory on older systems. WRONG.

Since swapping out to my ATi card proved that the full 3.0gig was accessible there's no reason it should eat system memory.

My nivida card is 512Mb. So even if it did take it out of my system ram I should still have 2.50Gb left. But I still get 2.25Gb.

Secondly since there is address space from 3.0->4.0Gb, the graphics card should use that and I should see my whole 3.0gig regardless.

Finally I read somewhere else that this can be fixed with an option in cetain BIOS-s called "Shared Memory", or "Memory Shadowing" and turn it OFF.

It's really annoying since the hidden RAM is not being used for any logical or illogical purpose, just wasted.

Since my last post I tried putting in an older BIOS and managed to go from 2.25Gb to 2.50Gb. A modest increase, better than nothing, but proves that it is not OS related and most likely BIOS or nVidia laziness.

Recommend you try latest or oldest stable BIOS to see if there's any difference or other options in BIOS menu. Would be great to enable it for all BIOS-s with a hack of some kind.

 

[VonDole]

I recently encountered this error where i have 1 x 2gb DDR2. When I checked in bios it shows 2gb is installed. But after booting in xp it only shows 1gb. what i did was i open boot.ini found in my case c:\boot.ini which i the default path in most xp normal installation. then i found a line that says something like maxmem=1024..that's the problem so i changed it to 2048 saved the changes and reboot.

that seemed to fix my problem..you might try this if this works.

*note i am running xp 64bit.

 

[mrtinfl]

In a computer all bytes in the memory system need a unique name. This is called an address. For example, if you have 2 GB of main memory, then there are 2147483648 bytes of RAM in your machine, each of which require an address for the operating system to communicate to it. To give these all an address you need 31 bits to do it. Now, if/when you have 32 bits, you can name 4 GB (2 bytes to the 32nd power = 4GB).

This is why the total addressable space available in a 32 bit OS is 4GB – the OS runs out of addresses and cannot communicate/locate any more bytes of memory because of that.

You may think ”Hey, 4GB of address space… 4GB of RAM… What’s the problem” The problem is that memory isn’t the only thing needing an address. If you install a total of 4GB worth of RAM, the system will detect/use/display less than 4GB of total memory because of address space allocation for other critical functions, such as:

- System BIOS (including motherboard, add-on cards, etc..)
- Motherboards resources
- Memory mapped I/O
- Configuration for AGP/PCI-Ex/PCI
- Other memory allocations for PCI devices

Different onboard devices and different add-on cards (devices) will result of different total memory size. e.g. more PCI cards installed will require more memory resources, resulting of less memory free for other uses.

This limitation applies to most chipsets & Windows XP/Vista 32-bit version operating systems. Again, this is a limitation of the Operating System not having enough address space to allocate to the system *and* the RAM. Not allocating address space to devices renders them inoperable. Not allocating addresses to RAM simply results in the unaddressed section not being used in an otherwise fully functional computer. Therefore the OS designers assign RAM last.

We can have long debates about mathematical fundamentals and discussions about why the original Windows designers couldn't allocate the full theoretical max of 36 bits of address space so that users today would be able to use more resource. But at the end of the day, the designers and engineers 'Didn't Then'. So we 'Can't Now'.


If you install a Windows operating system, and if more than 3GB memory is required for your system, then the below conditions must be met:

1. A memory controller which supports memory swap functionality is used. The latest chipsets like Intel 975X, 955X, Nvidia NF4 SLI Intel Edition, Nvidia NF4 SLI X16, AMD K8 and newer architectures can support the memory swap function.

2. Installation of Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can provide more than 4GB worth of address space.



Note: According to the latest Change Log published by Microsoft, Windows Vista 32bit SP1 will display the installed amount of RAM. This is a display change only.

I read your above thread and u seemed very knowledgable and i have been having a problem and not sure how to handle. I used wp xp pro sp3, i have 2 (2gb) memory total 4gb (corsair) and xfx ge force 7100 mb, intel pentium III xeon 2.67 ghz and ram only showing 2.87 ram out of 4gb. Now I understood your explanation above, all stuff on mb is onboard, i.e. no extra video, etc, the only thing is using a pci ethernet.

1. How do i free up some of that ram.
2. Every one in a while will get blue screen with no details, i.e. no errors, i.e page ..... driver.... Called mb people they say possible memory bad, but have done memory check and all seems fine. Was reading up on mb and some say to "adjust clock something in bio" is that something you know about? My email address is mrtinfl@bellsouth.net if there is anything u can help with.

 

[bugmenot1983]

If anyone is interested, I was able to fix my problem by upgrading my BIOS firmware.

Windows XP 32bit
4GB of RAM (2.99GB detected after the fix)
Intel DP43TF

 

[Guest]

Interesting. I have 2x1gb and 2x512 and it properly shows up as 3gb. I'd start by looking up your mobo and seeing if it has any restrictions on mixing ram sizes, and make sure your motherboard drivers/bios are up to date while you're there.

Yes, updating bios worked for me.
Had 1GB DDR and 512MB DDR, but bios recognized only 1GB. After updating bios (directly in Windows), after restarting already recognized 1,5GB. Thanks