It's possible that your computer is configured to use the remaining 7gb of RAM as virtual memory. To check this, please open the System Properties window and select the Advanced tab. Then, select the Performance Settings button and select the Advanced tab. There should be an option to change the Virtual Memory settings. Please make sure the Automatically manage paging file size for all drives box is unchecked, and then select the drive that contains the RAM. Make sure the Initial and Maximum size boxes are both set to the same value (the maximum size of your installed RAM). Finally, select Set and then OK to save your changes.