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Can I use "unused" ram as a ram drive?

Posted on 2009-07-14
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I have a 32bit version of Windows 7 and 4 GB of ram, but the system is only using 3 GB. Is it possible to use a RAMDRIVE with the wasted RAM? Or will installing a RAMDRIVE use some of the 3GB of system RAM?
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Question by:washy16
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by:johnb6767
ID: 24851233
It isnt wasted RAM, as it is being used for Kernel Mode processes. Bout the only thing you can do, is to upgrade to a 64bit OS.....
 
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by:LeeTutor
ID: 24851262
With a 32-bit OS, some of the 4 GB of RAM will not be available to the user for programs, RAM drives, etc., because some is used the system.  This is true for XP, Vista, Windows 7, etc.  This and a lot of variations are a very popular question at Experts-Exchange.  See the great replies posted by various experts in this Previously Answered Question at Experts Exchange:

http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Windows/XP/Q_24113152.html
XP Pro computer with 4 GB memory only showing 3.25GB, how can I get it to show 4gb?
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garycase earned 50 total points
ID: 24851383
"... It isnt wasted RAM, as it is being used for Kernel Mode processes ..." ==>  NO!!   The RAM is indeed "wasted" -- i.e. it can't be accessed because the system can't assign addresses to it.    The reason you don't "see" 4GB is that there aren't enough addresses left in the 4GB address space after various system-level addresses have been assigned.     Read the comments that LeeTutor and I wrote in the thread referred to in LeeTutor's comment above.

There IS, however, a way you can use the memory as a RamDisk ... although it's not free.    This program uses the physical address extensions feature to let you access the otherwise unused memory as a RamDisk -- and the "Plus" version will let you use even more memory (above 4GB) if your motherboard supports more than 4GB.      http://www.superspeed.com/desktop/ramdisk.php
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by:washy16
ID: 31603309
This program was exactly what I was looking for. Thanks a lot!
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by:johnb6767
ID: 24851690
How can the RAM be wasted when it is in use/reserved? I understand completely how the the 4gb limitation works, but I dont agree with it being wasted, as it is being reserved/assigned...
 
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by:garycase
ID: 24851745
No, it is not being "reserved/assigned".    The ADDRESS SPACE is being used ... NOT the memory.

Read the details in my post here:
http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Windows/XP/Q_24113152.html#23553824
(See the paragraph that starts with  " A 32-bit system can address 2^32 addressess ..."
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by:johnb6767
ID: 24851899
"A 32-bit system can address 2^32 addressess, which totals 4GB.   But certain system-level functions much be assigned addresses; and these are assigned from the "top" downward -- i.e. at the upper end of the address space.   These include such things as BIOS shadowing; PCI addresses; Video aperture; etc. ... and will typically use between 0.4GB to as much as 1.5GB (on systems with dual video cards with large amounts of memory).    After these addresses are assigned, whatever's left is available for your physical RAM. "
I have seen this post many times, and dont get me wrong, but when "But certain system-level functions much be assigned addresses; and these are assigned from the "top" downward -- i.e. at the upper end of the address space". I interpret that as non available space, whether or not it is in use. Hence, not wasted as it is being utilized....
Dont get me wrong, your the last person I wanna argue with on deep hardware technology questions, but maybe its just a verbage difference between how it is asked. I just dont see it as wasted, as the address space within the RAM is being used by the system level functions....
And FYI, I certainly am not objecting to the outcome of this thread.
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by:garycase
ID: 24851978
The ADDRESS SPACE is being used ==> thus it is not available for use by the physical RAM.

So, for example, if you have 4GB of RAM installed, but the system assigns 800K of addresses to system-level functions (e.g. those things I listed above), then only 3.2GB of RAM is assigned addresses, and there's 800KB of unused (i.e. "wasted") RAM.      On an SLI system with two video cards, this can be a substantial amount of space.    The lowest I've seen is 2.2GB of available RAM (thus 1.8GB of "wasted" unused RAM) ... but it can go even lower than that if you have two 1GB video cards installed.

You're confusing the 4GB ADDRESS SPACE (which is always fully utilized) with the physical RAM.

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by:johnb6767
ID: 24852199
LOL..... Had this nice long thread typed up, just decided to delete it... Figured it would be easier.....   :)
Think its just a matter of verbage at this point.....  
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by:johnb6767
ID: 24852239
Oh, and BTW, congrats on the MVP Selection. Was nominated last year for MS Outlook, but didnt get selected.... Kinda hoping to get spotted for Windows XP/Consumer Security.....
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by:garycase
ID: 24852416
Thanks.
Do you understand that the memory is not being used?

One more example (just for grins) ...

Suppose a particular system requires 900KB of address space for the functions I've outlined many times (in the paragraph you quoted). ... and that there is 3GB of installed RAM in that system. In that case, after assignment of addresses for the various system-level functions, there is 3.1GB of address space remaining, so all 3GB of RAM can be assigned addresses ... and the system will "see" 3GB of RAM -- all that's installed.

If you now update the RAM to 4GB, the only thing that will change is that the system will "see" 3.1GB of RAM. There will be 900GB of installed RAM that is not being used in any way -- because it can't be assigned addresses.

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by:johnb6767
ID: 24852642
Yes, I understand that. I really DO understand the difference between the Address Space/Physical RAM. I know the memory isnt being used, but I just didnt see it as a waste, as the original poster asked...  I honestly had never seen an app that could use PAE on a 32 bit system, without it being a Windows Server Edition that support 36bit addressing). In that aspect of it, I didnt think it was a waste, as there is no more Address Space available for the remainder of the RAM, once the System Level processes have been assigned....
BTW, a very unique explanation on it.....
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by:johnb6767
ID: 24852706
That doesnt even sound right when I re read it...... I am trying to explain my thought processes, but I cant get them on paper here....
 
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by:garycase
ID: 24852763
Most modern systems have BIOS and CPU support for PAE -- it's only that the OS's don't support using memory above the 4GB boundary except for enterprise versions of Server 2003 and 2008.

But that's simply a design choice by Microsoft -- clearly the "standard" versions of 2003 and 2008 could also use additional memory if they elected to allow it ... but that's one of the points of differentiation between "standard" and "enterprise".     In fact, Vista shares the same foundation code as Server 2008, and the code to manage memory above 4GB is actually in the Vista OS ... it's simply not enabled.    I've actually seen a Vista x32 system using 8GB -- but (a) don't recommend it; (b) don't do it myself;  and (c) won't provide any details/links regarding it.    Such modifications are "dangerous" in the sense that any update is likely to "break" it.
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by:johnb6767
ID: 24852932
I have 4 kids and a wife, anything with 8gb RAM is out of my reach.....   :)
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