A 32-bit operating system, such as the Windows Vista® or the Windows® XP operating system, can only generate 4GB of memory addresses. Since some of these memory addresses are used by certain hardware components, there are not enough memory addresses left to map 4GB of Random Access Memory (RAM). This issue can cause the operating system to report the amount of RAM as approximately 3GB.
Some examples of hardware components that use memory addresses are:
- Graphics adapter
- PCI bus
- PCI Express support which may require up to 758MB
- BIOS, ACPI and legacy video support
Use the following procedure to view the actual amount of physically installed RAM.
- Click the Start button and then click All Programs.
- In the All Programs menu, click VAIO Central.
- In the VAIO Central window, on the Categories tab, click the plus (+) next to System Information to expand the selection.
- Under System Information, click to select System Information and then click the Open button.
- In the System Information window, the actual amount of physically installed memory is displayed next to System Memory.
- If VAIO Central does not report the correct amount of physically installed system memory, verify the correct memory type and configuration is being used.
- Windows Vista Service Pack 1 reports the amount of system memory correctly.