Physical memory limits for Windows 7

Maximum limits on physical memory (RAM) that Windows 7 can address vary depending on both the Windows version and between 32-bit and 64-bit versions....

Version Limit in 32-bit Windows
Windows 7 Ultimate           -    4 GB
Windows 7 Enterprise        -    4 GB
Windows 7 Professional     -    4 GB
Windows 7 Home Premium -   4 GB
Windows 7 Home Basic     -    4 GB
Windows 7 Starter             -    2 GB

Limit in 64-bit Windows

Windows 7 Ultimate           -    192 GB

Windows 7 Enterprise        -    192 GB

Windows 7 Professional     -    192 GB

Windows 7 Home Premium -   16 GB

Windows 7 Home Basic     -    8 GB

Windows 7 Starter             -    N/A