As Microsoft says Windows (32) has a 4GB
address space, which must be used to address physical RAM, as well as other things.
Other things like:
- System ROM
- APIC(s)
- Integrated PCI devices, such as network connectors and SCSI controllers
- PCI cards
- Graphics card
- PCI Express cards (if applicable)
Source:
4GB RAM in Windows XP
I have a 1Gig Vram and Windows only detecting 2.99 of my 4Gig Physical RAM. Had I gotten 500M video card, maybe Windows will detect 3.5Gig? (assuming there are no other PCI cards installed)