Windows 7 question regarding usage of memory

When using a 32-bit operating system like Windows 7, the system can only address a maximum of 4 GB of RAM. However, due to system hardware and BIOS limitations, the usable RAM may be less than the physical RAM installed. In your case, with 4 GB of RAM installed, the operating system recognizes only 3 GB as usable, with the missing 1 GB likely being reserved by hardware or BIOS. Regarding the shared memory for your on-board Nvidia graphics card, the 128 MB RAM used for graphics processing is typically allocated from the system RAM, not from the RAM that is not usable by the operating system. This shared memory is dynamically allocated and used for graphics processing, allowing the graphics card to use system memory when needed. In summary:

• The 128 MB RAM used by the onboard Nvidia graphics card is allocated from the 3 GB of RAM that is recognized and usable by the operating system.
• The remaining 1 GB of RAM that is not usable by the operating system is likely reserved by hardware or BIOS limitations and is not used for graphics processing.

If you encounter frequent blue screens when using a 64-bit Windows 7 installation with your Quad-core AMD machine, it may indicate compatibility or driver issues. It's essential to ensure that all hardware drivers are up to date and compatible with a 64-bit operating system to address the blue screen errors.