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Hardware Reserved Memory is high - advice/opinions required..

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#1 ade666


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Posted 10 May 2013 - 03:54 AM


Joined today just so I can put this little problem out there and see if someone can shed some light on it as it has baffled me somewhat.

I have 4gb of RAM installed on Windows 7 32-bit , I know that 32-bit won`t allow me to use all of it, but I believe I should be able to access at least 3.5Gb.
Anyway, I can only use 2.5Gb as alot is Hardware Reserved ( 1538Mb to be precise ), I could accept that fact if the following didn`t happen - this is what is confusing me no end.

When I remove one strip of RAM ( I have 2x 2gb ) , the memory obviously drops to 2gb, BUT, the hardware reserved memory also drops  - to 2MB!!

As soon as I put the other strip back in and go back to 4Gb I`m suddenly hit with the 1538Mb Hardware reserved again.

To try diagnosing things, I removed my PCI graphics card and used the onboard VGA. The hardware reserved memory then dropped to 750Mb, so I came to the conclusion that the graphics card is taking 750mb. But ( this is what confuses me ) , when I only have 2gb installed the hardware reserved is 2mb , so nothing is been reserved for the graphics card in this case, and whatever is using the other 750mb doesn`t take it either!

I need the VGA card installed as I use two monitors at work and the card is dual head.

Can anyone tell me why the hardware reserved memory rockets up to 1538Mb when I have the 4gb installed, yet is only 2mb with 2gb installed?
Surely if the VGA card ( and whatever else ) needs the 1538mb then it would still try and take it with only 2gb installed.

I really need to try and free up this reserved memory as I need to run Virtual PCs on my machine and have a few other programs open at once. It`s just bugging me like hell now!

Cheers all,



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#2 anyrepli


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Posted 10 May 2013 - 06:17 AM

Hello Ade,


Everything you describes sounds about right to me. The more memory you add, the more Windows will try to allocate; however, with only 2 GBs installed, windows (probably) cannot allocate memory to specific functions because it may have to swap programs in and out of memory as required. However, once you up it to 4 GBs, a new allocation scheme kicks in. First off, windows will take (up to) a full 1GB of memory off the top due to your 32 bit OS limitation. How much it takes off depends on your chipset limitations and/or your bios restrictions. So, when you upped the memory to 4 GBs, windows decided there was now enough memory to allocate a specific amount to the graphics function, and it appears that allocation will vary (on your machine) based on whether or not you are using onboard graphics or an external graphics card.

#3 ade666

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Posted 13 May 2013 - 01:52 AM

Thanks for your answer anyrepli, on further investigation, I looked at the Windows Experience Index, and on the page that shows the detailed performance and system information, the details listed next to the  `Gaming graphics` component stated `1535Mb Total available graphics memory`. So this is obviously where the memory is going, so that clears that up.

Your answer explains why the allocated amount changes depending on total memory installed, I had no idea it worked like that. I would have thought a piece of hardware requiring system memory would take what it wanted regardless.
I find it odd that the graphics card demands that amount of memory when 4Gb is installed. Its only a basic dual head pci card so that I can run two monitors at once. Currently is has more memory than my GTX560i gaming card at home! Thats only 1Gb I think.

Is there any way I can lower the amount of memory the card is taking? It can obviously run on less - I think it only uses 756Mb when I only install 2Gb to the PC.

Anyway, the mstery appears to be solved, I`m just not happy with my greedy graphics card! :)

#4 Anshad Edavana

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Posted 13 May 2013 - 02:09 AM



There is a way to limit the automatic allocation of RAM by Windows. What you need to use the optional "3GB" switch. Here is the technical explanation by Microsoft :




Here is a how to guide by Autodesk : http://www.autodesk.in/adsk/servlet/ps/dl/item?siteID=123112&id=9583842&linkID=9240617


If you encounter any stability issues after using the switch, you can disable it.


Using the "3gb" switch is not recommended as it won't give the system any performance improvement. In short words, 32 bit Windows kernel is designed to allocate 2 GB RAM for user mode apps and remaining 2 GB for kernel mode apps. This is the recommended configuration and changing it may cause instabilities. There is nothing wrong with your system.

Edited by Anshad Edavana, 13 May 2013 - 02:24 AM.

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