[Nethfel]

Hi all,

Ok - first off - before everyone jumps one a few things about the windows install:

1) This is XP 32, it is installed and running normally.
2) I am fully aware that the max that XP 32 can access is 4 gigs, once you take out certain memory access, video memory, etc. reality is more between 3.25 and 3.5 gigs.
3) My system has 8 gigs of ram, I know I can't access that much without a 64 bit OS installed, I am not moving my bootcamp to Vista, I really don't mind not having all 8 gigs.

Now, what does bug me is I am not getting the 3.x gig I should see with XP 32 - instead I'm seeing around 2.x gig.

Now, I remember reading about this somewhere, a while back, but I can't for the life of me remember where it was nor what search terms brought it up. It was an issue someone else ran into as well and either it was a normal occurance due to the way XP 32 ran on a system like mine (Mac Pro 2xquad core, 8 gig) or it was something else that was adjustable, but I'm not sure which. and of course, since I didn't book mark it at the time, I can't find the page any more.

Anyone who either knows the answer, or knows where this reference is so I can go find it again, I'd be most appreciative!

[cwa107]

How much memory does the Nvidia card have on-board?

[Nethfel]

it's a 512, but I saw the same issue when I had the radeon 2600xt installed which only has 256mb ram - but it was a good thought =)

[louishen]

I believe that 512 meg is lost due to the graphics card (but I bet you know that one), so you are already down to 3.5 gig of space, add in various drivers that load up and that will probably explain the remainder of the lost memory

Why Windows is not detecting the 4 GB of RAM installed? - The solution

[bikalpapaudel]

^ Mac Pro has a dedicated card I guess. So hoe come Windows show lesser System RAM?

And loading drivers wont make one 'loose' memory in the sense that you dont see it all.

[louishen]

THis explanation is from the MS site

This behavior is the expected result of certain hardware and software factors.

Various devices in a typical computer require memory-mapped access. This is known as memory-mapped I/O (MMIO). For the MMIO space to be available to 32-bit operating systems, the MMIO space must reside within the first 4 GB of address space.

For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.

The reduction in available system memory depends on the devices that are installed in the computer. However, to avoid potential driver compatibility issues, the 32-bit versions of Windows Vista limit the total available memory to 3.12 GB. See the "More information" section for information about potential driver compatibility issues.

If a computer has many installed devices, the available memory may be reduced to 3 GB or less. However, the maximum memory available in 32-bit versions of Windows Vista is typically 3.12 GB.

The system memory that is reported in the System Information dialog box in Windows Vista is less than you expect if 4 GB of RAM is installed

[Nethfel]

Ok, my system doesn't have a ton of installed devices, the system, the video card, 2 cd rom drives, the 4 satas, keyboard, mouse. I should see around 3 gigs, not around 2 gigs. There is no way I have enough "devices" to absorb the difference between about 3 gigs and about 2 gigs.

As I mentioned, I fully expected to not see 4 gigs - this is something I understood a long time ago, but only seeing 2 gigs instead of about 3 is what's making me curious.

And louishen - that only explains why there would be about 3 gigs, not what I'm seeing - 2 gigs, a full gig less (as I mentioned before in this post, and my original post, I understand the meaning behind why you don't see 4 gigs in a 4 gig system on 32 bit OS)

If I had 2.75 or more gigs free, I probably wouldn't be curious.

Oh well, in the long run it's not a huge deal because of the fact that I only use the windows boot to play games anyway - I was just wondering why the amount of ram is so substantially lower then what would normally be there on a 4 gig system with 32 bit OS.

[Nethfel]

I should note, I did make one mistake in my original post that I checked out today when I booted into XP - I only show 1.99 GB ram, similar to what someone with only 2 Gigs installed would see. I don't see what "quantity" of devices could exist in my Mac Pro that would absorb 1 to 1.25 gigs worth of address space (I'm considering a 32 bit OS should show around 3 to 3.25, which means that something is causing me to loose an additional 1 to 1.25 gigs of ram due to address mapping).

[guynsandiego]

I would have to agree with the original poster that there is some issue beyond simply the resources being used, as I tried 2gb, 8gb, and 10gb ram with the same 1.99gb ram showing on My Computer properties, and the approx. 1.22gb Physical Memory Available in the System Information. The System Information does see the correct amount of memory installed, but much of it magically disappears. I should see around 3 to 3.5gb in all those configurations except the 2gb one. So I second him in that he is right. The solutions given are not correct. otherwise, the Physical Memory and the memory showing in the My Computer properties should be changing. Mine is a MacPro 1.1 from 2006, with xp pro 32bit in bootcamp. I hope this post will shed some light to this issue and revive the topic so that others may give more input that may explain this problem, and hopefully solve it.

Thanks!