# Missing Ram (3.5Gb on 4Gb Machine)



## TrevaUk (Apr 19, 2008)

My machine has 4GB installed but only 3.5 Gb (3582mb) is usable
I am using Vista Ultimate x64 Edition

I recently upgraded my OS from XP Pro 32 to Vista Ultimate 64 but I'm still missing about 512 mbs of my installed memory.

The memory is installed is 2Gb X 2 6400 DDR2 800(Matched Pair) in dual channel configuration. brand 'GeIL Black Dragon'
I have room for another 2 memory cards for a total of 8Gb Max.

Motherboard is an ASUS M2N-e ATX
CPu is AMD Athlon64 X2 Dual Core Processor 3800+ (2.01GHz)

Graphics Card is a Nvidia Geforce 8800 GTX OC2 768mb

*Image*


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## OMGmissinglink (Sep 24, 2006)

If your using sli gpu's mapping will use aprox 500mb.


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## TrevaUk (Apr 19, 2008)

OMGmissinglink said:


> If your using sli gpu's mapping will use aprox 500mb.


I don't have SLi, just a single GPU


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## OMGmissinglink (Sep 24, 2006)

TrevaUk said:


> I don't have SLi, just a single GPU



Single GPU will map half of 500gb's other devices & OS settings in your system are using the other half.. 

If its not broke don't fix it !!


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## magnethead (Mar 18, 2006)

OMGmissinglink said:


> Single GPU will map half of 500gb's other devices & OS settings in your system are using the other half..
> 
> If its not broke don't fix it !!


I don't see it taking any 256 on my system for my 9800?

this is a desktop correct?

I still agree something is wrong.


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## OMGmissinglink (Sep 24, 2006)

Vista 64bit misreporting 4gb ram
http://support.microsoft.com/kb/929605

There is another artical that when sli is used Vista OS maps out aprox 500mb..

http://www.nerdgrind.com/windows-vista-shows-less-than-4-gb-of-ram-installed/


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## airless (Aug 3, 2008)

I had 2gb in my machine and it said i have 1gb. I figured out the RAM wasn't in correctly. Try that.


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## TrevaUk (Apr 19, 2008)

UPDATE: I have just looked at the bios and bios reports 4096MB Installed but only 3583MB Usable, see pic









I'm not using SLI, just one GPU (Geforce 8800 GTX 768MB), This GPU has it's own memory and does not need system ram.
This is a desktop PC


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## McNinja (Jun 22, 2008)

hey TrevaUK look at OMGmissinglink's first link it explain's it under workaround

this one http://support.microsoft.com/kb/929605

and why are you so worried??? it'll never use all of the 3.5gb


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## justpassingby (Mar 11, 2007)

All is explained in the microsoft support article (see post#6).

The amount of reported RAM will be the amount of physical RAM minus the amount of physical address space reserved for the other PCI devices. Enter the BIOS and see if there's a memory remap feature (refer to the motherboard's manual). If the motherboard suports it this will allow to map the PCI devices' addresses above the usual 4GB limit.

See this for a visual explanation (Vista and XP allocate the RAM in the same way) :
http://h20331.www2.hp.com/Hpsub/downloads/RAM_Allocation_w-WinXP_HP_MWP_x64.pdf


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