# Not all installed RAM showing up in XP



## Indiana627 (Nov 18, 2005)

I had a total of 2GB of RAM installed (4 x 512MB) in my XP Pro 32 bit PC. I just installed another 2GB by removing 2 of the 512MB, so now I have 2 x 2GB and 2 x 512MB for a total of 5GB (and yes they are installed in the correct matching pairs).

When I started up I got the message that the memory had changed and to hit F2 to enter setup, which I did and it confirmed 5GB is now installed. So I continuted to load windows. I then right clicked on My Compuer > Properties and it only lists 3.37GB.

I then went to System Info and on the Summary screen it lists:
Total Physical Memory 5,120.00 MB
Available Physical Memory 2.85 GB
Total Virtual Memory 2.00 GB
Available Virtual Memory 1.96 GB
Page File Space 5.21 GB

I added more RAM since I do a lot of graphics on this PC and wanted better performance, but now I'm not sure if I'm using all the additional RAM I bought. Is some of my new RAM not being used? 

I did some searching and found /PAE switch, but I've read conflicting reports if that works in XP, or only in Server 2003.

Is there a way to get all my RAM to be used? Thanks.


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## dmspen (Dec 1, 2006)

OK, XP 32 bit version cannot recognize more than 3.5 G of RAM. To use all your ram, you'd have to get XP 64 bit OS which you really don't want. Not sure if XP server OS will recognize it.


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## Indiana627 (Nov 18, 2005)

Then why did my Dell manual tell me it can use up to 4GB?


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## phat78boy (Sep 12, 2007)

XP always reports between 3-10 percent less memory then the total amount installed. The reason is system devices eat a percentage of memory for device mappings and such. The amount taken can ranged depending on the system and what devices you have installed. This amount of memory is gone before Windows even boots. Thus Windows only reports what is actually available (left over).

So yes, you can have 4GB of memory installed. The memory not being seen by XP is actually still there and is actually in use by your system. Your not losing anything.


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## Indiana627 (Nov 18, 2005)

OK I have a side question. There is another slow computer here that I'd like to put the 2 sticks of RAM I took out of mine in to. I did a memory scan at crucial.com and it called for PC2700 memory, but the memory I'd like to put in it is PC4200. Will that work without causing any problems? Thanks.


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## Pinion413 (Oct 21, 2007)

Indiana627 said:


> OK I have a side question. There is another slow computer here that I'd like to put the 2 sticks of RAM I took out of mine in to. I did a memory scan at crucial.com and it called for PC2700 memory, but the memory I'd like to put in it is PC4200. Will that work without causing any problems? Thanks.


The machine you want to put the RAM into calls for PC2700?

If that's the case, then no, you can't put PC4200 into it. For one, PC4200 is DDR2 (533MHz) where PC2700 is straight DDR (333MHz). For another, PC2100/2700/3200 DDR are 184-pin DIMM's where DDR2 DIMM's are 240 pin. It won't fit in the motherboard's RAM slots. Sorry.


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## funhouse69 (Mar 26, 2007)

Indiana627 said:


> Then why did my Dell manual tell me it can use up to 4GB?


The manual is telling you what the motherboard and its chipset will support it doesn't take in to account what the OS will support as most motherboard will support several different operating systems.

It has been discussed for quite some time now... Just throw in 4GB Windows limit in google and you will get more hits than you can read.

As mentioned to get past this you will need a different OS and none of the 32 Bit XP's will do it so you'd have to look at Vista or a server edition of a MS Product.


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