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1.5GB memory hole with 256 MB video card !?

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May 12, 2009 10:29:24 PM

With 4GB RAM and a 8400 GS (256MB) video card on a EGVA X58 SLI MB, I am only seeing 2.5GB RAM in XP.

I know some is lost to the memory hole, but why is 1.5GB (!) being lost using such a relatively small video card?

What can I do to maximize the available RAM? The BIOS doesn't seem to have a memory remapping option.

This is not a gaming machine. My constraints are that I must stick with XP 32 bit and I want to maximize the available RAM. I don't need a good video card. If I choose some even lower end video card, would that help at all?

I would be satisfied if Windows could see 3GB or 3.25 GB, but right now, 2.5GB is too much of a loss.

Thank you.
a b } Memory
a b U Graphics card
May 12, 2009 10:44:13 PM

In 32 bit Windows operating systems, the total addressable space available is 4GB. If you installed total 4GB memory, the system will detect 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.

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

1. The 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. Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can address more than 4GB memory.



Note: According to the latest Change Log published my Microsoft, Windows Vista 32bit SP1 will display the installed amount of RAM. This is a display change only.
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a b } Memory
a b U Graphics card
May 12, 2009 10:45:05 PM

Translation of the above in one sentence: If you must stick with XP 32, then you are stuck with the amount of RAM you have now because your chosen operating system does not have enough address space.
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Related resources
May 12, 2009 10:52:16 PM

Quote:
1. The 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.


My MB is x58 -- does it support memory swap? I cannot see that function in the BIOS.

Also, are you saying that if I were to get a 64 MB video card, my memory hole would still be > 1GB?
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a b } Memory
a b U Graphics card
May 12, 2009 10:56:36 PM

Your motherboard manual will have it in there, though my experience is it's generally at the proper setting out of the box.

And regarding the amount of RAM available: That will vary according to your install. i.e., if you have a motherboard with a lot of devices/resources then it will eat more address space. Same for installed devices.

Anyways - read your motherboard manual, or check with EVGA (their support guys are excellent) to locate the proper setting.
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a b } Memory
a c 171 U Graphics card
May 12, 2009 11:40:54 PM

Does your 8400GS support "hyper" memory? (or whatever Nvidia calls using system ram to get up to 512MB effective Vram.) If your card does support this feature, and its turned on, then you have 256MBs of address space being used to bump your Vram up to 512, plus whatever windows uses to keep track of whats in video memory. (its less then 1:1.) This means your losing probably over half a gig just for this video card.

I have a P35 chipset motherboard with 4GBs of ram and the 8800GS. I see 3.2GBs of memory. I don't have many PCI cards installed, so depending on your configuration that might be your problem. I'd also take a look at some bad bios settings, as I would think you should see more then what you have.
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a b } Memory
a c 106 U Graphics card
May 12, 2009 11:46:33 PM

Seems about right. The more options your motherboard has the more of a memory address space it's going to take up. You can always go into your BIOS and start disabling devices you don't need (firewire, unused serial and USB ports, etc.) but the effect will really only be minimal at best. That's kinda funny though considering that systems I've built with the ASRock780GFullHD and a 512MB GPU usually show 3.0-3.2GB of the 4GB of Ram with a 32-bit OS. Seeing as I myself am using two 512MB cards upgrading to 4GB won't do me a whole lot of good without a 64-bit OS, which I'll probably be forced to get soon enough ^_^. Figure I may as well wait till they work some bugs out of win7, but we'll see.
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May 13, 2009 12:03:41 AM

So far I have not plugged in any PCI devices, it is just the video card, one SATA HD, one PATA DVD burner. I will check into the "hyper" memory and with the motherboard manual and eVGA support. I think it is possible that this feature loaded X58 board has a lot of memory mapped resources.

I'd be curious as to what the maximum avail. RAM anyone has seen in a X58 MB + WinXP 32 bit install. Anyone have a similar config?
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May 13, 2009 10:46:05 AM

The hole is often aligned on a boundary, so the hole gets bigger than the actual usage. You can check what devices are mapped in msinfo32
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a b U Graphics card
May 13, 2009 1:44:00 PM

why stick with such a dinosaur of an OS with your rig? DITCH WINDOWS XP (X86)
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May 13, 2009 7:42:28 PM

I wish I could, but as I said in original post, I am constrained to use XP 32-bit, because of driver support for instrumentation it needs to control, for which no 64-bit drivers are available.
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May 13, 2009 8:27:44 PM

mikrev007 said:
The hole is often aligned on a boundary, so the hole gets bigger than the actual usage. You can check what devices are mapped in msinfo32


How do I interpret the msinfo32/Memory output? Below I print the size of each item which is greater than 1MB:

8 MB 0x9F800000-0x9FFFFFFF System board
16 MB 0xDE000000-0xDEFFFFFF NVIDIA GeForce 8400 GS
64 MB 0xDC000000-0xDFFFFFFF Intel(R) 5520/5500/X58 I/O Hub PCI Express Root Port 3 - 340A
64 MB 0xDC000000-0xDFFFFFFF NVIDIA GeForce 8400 GS
256 MB 0xC0000000-0xCFFFFFFF Intel(R) 5520/5500/X58 I/O Hub PCI Express Root Port 3 - 340A
256 MB 0xE0000000-0xEFFFFFFF Motherboard resources
256 MB 0xC0000000-0xCFFFFFFF NVIDIA GeForce 8400 GS
1516 MB 0xA0000000-0xFEBFFFFF PCI bus
2551 MB 0x100000-0x9F78FFFF System board


So the "System Board" is my available RAM, and the PCI bus is the reason for my 1.5 GB hole?
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May 13, 2009 10:08:09 PM

unprovoked said:
With 4GB RAM and a 8400 GS (256MB) video card on a EGVA X58 SLI MB, I am only seeing 2.5GB RAM in XP.

I know some is lost to the memory hole, but why is 1.5GB (!) being lost using such a relatively small video card?

What can I do to maximize the available RAM? The BIOS doesn't seem to have a memory remapping option.

This is not a gaming machine. My constraints are that I must stick with XP 32 bit and I want to maximize the available RAM. I don't need a good video card. If I choose some even lower end video card, would that help at all?

I would be satisfied if Windows could see 3GB or 3.25 GB, but right now, 2.5GB is too much of a loss.

Thank you.


Just get a 64bit OS before this thread turns into a war of words.
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a b U Graphics card
May 14, 2009 3:10:17 AM

What instrumentation is it that you are dealing with?
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