I understand that if I have an integrated graphics and 4 gb of ram, windows 7 needs to address some of it o the integrated ones. However how come if I have a discrete graphics card with 1 gb of vram, the os can only see about 2.8 gb of ram? Is this because 32 bit can only address 4gb of total ram (gfx + normal ram)?
32-bit Windows Max RAM – Using Discrete Graphics Card
32-bitmemorypaevramwindows 7
Best Answer
A 32-bit OS without PAE has a maximum address range of 4GB of physical memory. With an integrated graphics card, some of the RAM is used by the GPU. With an external graphics card, some of the address space is used for hardware mappings into the VRAM, but it is not as large as the amount of memory on the card. Typically, a discrete GPU needs about 256MB of mapped space regardless of how much memory is on the card. Other hardware mappings typically need around 256MB in total. Typically a 4GB machine with a 32-bit OS without PAE and a discrete graphics card will have 3.2GB to 3.5GB of usable RAM.
Note that if your BIOS has a specific setting for a 32-bit OS, it will keep the mappings to a minimum to allow more usable memory with a 32-bit OS. Usually the setting is called "Memory remapping". Turn if off if you're using a 32-bit OS without PAE.