32 bit Windows’ support only 4 GB of RAM except 32 bit server editions which can read more than 4 GB. In case of Windows Vista, Windows 7 (and also Windows 8) 32 bit versions (x86), up to 3.50 GB of RAM is usable even if you have installed more than 4 GB of RAM. This is due to PAE (physical address extension) limitation of operating system. By enabling PAE, one can access more than 4 GB RAM on 32 bit version of Windows as well if processor supports x64 architecture.
32 bit Server editions of Windows can access more than 4 GB of RAM because they have pre enabled PAE. In Past, Windows 2000 Server could not read more than 4 GB of RAM but Windows 2000 Advanced Server and Windows 2000 DataCentre Server editions were designed to take advantage of more than 4 GB of RAM.
If you want to get real benefit of more RAM, buy 64 bit edition of Windows. Before buying, make sure your processor can support 64 bit operating system.
–To read about Memory Limits for different versions and different editions of windows, visit this link:
–To learn more about PAE and how to enable it, check this link: