Why Windows Vista only sees 3GB memory in a PC with 4GB RAM

4sysops.com — One of the many reasons we love to hate Windows Vista. What is astonishing is how Microsoft has updated the OS to show the correct amount of RAM but what users who may not know Vista's limitations is that the Vista OS can only use 3.12 GB of RAM. So they are basically wasting their money with out knowing. Apr 11, 2008 View in Crawl 4