If you are running Windows 7 32 bit and have 4 GB of RAM you may have noticed that within the device manager, Windows notes:
Installed memory (RAM): 4.00 GB (3.24 GB usable).
In the 32 bit version of Windows 7 only 3.2 to 3.5 GB of RAM is usable by the operating system. By patching the kernel the RAM limit can be increased up to 64 GB. The 4GB-RAMPatch.exe is available here and removes this lock.
Note: Once you have patched your kernel I recommend running:
bcdedit /set {current} description "Windows 7 No RAM Lock"
This will change the German menu item (Windows 7 ohne DDR-RAM Sperre) to an English translation.
You can find out more at Unwave’s website.