What you are seeing is normal for a 32-bit operating system. With 32-bit xp or vista with 4Gb of memory installed only 3-3.5 is usually visible. http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&cs=19&dl=false&l=en&s=dhs&docid=BF4C8393BFC74A83B9EC318630B9CE7D&doclang=en

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@dageezerus wrote:

500 MB is reserved for IO Processes of t5he PCI-E bus.  THe RAM is used, it is just not reported as "Available"

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I don't think that is right.  The address space of that 500mb is reserved for ports and things, I don't think it is actually using the memory.  In other words, for the computer to talk to any hardware (ports or memory) it needs an address.  "32 bit" means there is 4gb worth of addresses.  Your computer is using the first 500mb of addresses to point to non-memory hardware, so that only leaves 3.5gb of addresses left to access memory.  So the extra 500mb of memory is not accessible by the computer. 

 

Otherwise, if the hardware actually needed the 500mb of memory to share or give to it's ports, you would always see that drop in memory (when you put in 2gb, you would only have access to 1.5gb).  Of course, I these are rough numbers and this is unconfirmed information, it's just how I think of the memory issues with 32-bit vs 64-bit OS's.  When you move to a 64-bit OS, there is 64 bits of addresses available (2 to the power of 64 instead of 2 to the power of 32).

 

32 bit = 4,294,967,296 (4 gb)

64 bit =  18,446,744,073,709,551,616 (18,446,744 gb  :smileyhappy:)