Windows 7 Starter Maximum Physical Memory - RAM (GB) 2
Windows 7 Home Basic, Home Premium, Professional, Enterprise, Ultimate
(32-bit)
Maximum Physical Memory - RAM (GB) 4
Windows 7 Home Basic (64-bit) Maximum Physical Memory - RAM (GB) 8
Windows 7 Home Premium (64-bit) Maximum Physical Memory - RAM (GB) 16
Windows 7 Professional, Enterprise, Ultimate (64-bit) Maximum Physical
Memory - RAM (GB) 192
Source:
http://en.wikipedia.org/wiki/Physical_Address_Extension
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