Ever wondered how much memory (RAM) you can put in your machine?
Besides the physical number of slots for RAM, here are the Windows limitations. As you will see the Windows answer for more memory is ’64 bit’.
Some key points here:
- For Windows XP / Vista 32 bit have at least 2GB but try for 4GB
- 32 bit Windows (XP or Vista or 7) can only address 4GB of RAM, anything more is completely unused.
(It really ends up being between 3.0GB and 3.5GB since 512MB is lost due to PCI Architecture and 256MB is lost for the Video Card (or whatever memory the card has). - 64 bit Vista can only be installed on a 64 bit machine.
- 32 bit Vista / XP can be installed on a 32 bit or a 64 bit machine.
- In the 64 bit OS, 64 bit drivers must be signed and 32 bit drivers are not supported.
- Programs must be written for 64 bit in order to take advantage of these features.
Office 2007 is still a 32 bit program but almost all features will work on a 64 bit OS.
Windows Vista Compatibility Center
http://www.microsoft.com/windows/compatibility
To check for 64 bit software compatibility
- Click the ‘software’ tab
- Then after finding software make sure the system type (along the left) is ’64-bit Windows Vista’
Memory Limits for Windows Releases
http://msdn.microsoft.com/en-us/library/aa366778.aspx
Physical Memory Limits: Windows XP
The following table specifies the limits on physical memory for Windows XP.
| Version | Limit in 32-bit Windows | Limit in 64-bit Windows |
| Windows XP | 4 GB (but really 3.5GB)
Less 512MB for PCI Architecture Less 256MB for Video Card (or whatever memory the card has) |
128 GB |
| Windows XP Starter Edition | 512 MB | Not applicable |
Physical Memory Limits: Windows Vista
The following table specifies the limits on physical memory for Windows Vista.
| Version | Limit in 32-bit Windows | Limit in 64-bit Windows* |
| Windows Vista Ultimate | 4 GB | 128 GB |
| Windows Vista Enterprise | 4 GB | 128 GB |
| Windows Vista Business | 4 GB | 128 GB |
| Windows Vista Home Premium | 4 GB | 16 GB |
| Windows Vista Home Basic | 4 GB | 8 GB |
| Windows Vista Starter | 1 GB | Not applicable |
Memory and Address Space Limits
| Memory type | Limit in 32-bit Windows | Limit in 64-bit Windows |
| User-mode virtual address space for each 32-bit process | 2 GB
Up to 3 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE and 4GT |
2 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE cleared (default)
4 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE set |
