The problems were the memory management got flakey when streaming large files into RAM from a microscope camera. Mostly for recording object motion where many large images were recorded over several seconds and streamed into memory. Systems with 4 GB were a bit flakey while reducing the system memory to 2 GB apparently fixed the problem. I was looking for a fundamental reason if windows just has problems managing the maximum amount of memory for a 32 bit system.
32-bit Windows may have problems with it, however Windows XP 64-bit edition can handle 64GB of RAM.
Just a little correction here. Yes XP 64 Can handle 64GB of Ram but that is NOT its upper limit. The Upper Practical Limit is 16TB (Tera Bytes) of Physical System Memory and the Upper theoretical Limit is 2^64 - 1/2 times the number of Pages of offsets (typically about 5% of total) Bytes of available System Memory which equals approximately 15.9QB (Quadrillion Bytes) of available address space
Has anyone had reliability issues with 4 GB of memory in Windows XP?
Some say yes others say no I'm just looking for stories.
The probem may have been that you need to add the /3GB switch to the boot.ini for your install(this is per app). Also, your mobo may have something to do with it. Did you try using SPD(auto-configure in the BIOS) for the RAM? The way DataCenter accesses more than 2GB is using the /PAE switch. Also did you turn off the pagefile. Windows gets confused. As far as X64, the limitation for memory size is the processor. Right now AMD has 48-bit addressing so it supports 2 to the 48th power bytes. Intel does I believe have full 64-bit addressing, but even 48-bit is WAYYYYYYYY beyond how much RAM you can add to a single system.