Question : Problem: 32-Bit Memory Limitations & Video Card

I have a machine that I have just upgraded to 4 GB DDR2 Dual Channel ram. I am running Windows Vista 32-bit and I have 2 video cards with identical chipsets (BFG & Asus nVidia 8500GT 512 MB).

When I place the BFG card in my machine, the reported memory in Windows Vista appears to be 2.63 GB RAM (3200 MB - 512 MB). When I place the Asus card in my machine, the reported amount of memory from Windows Vista is 3.13 GB (3200 MB) of RAM.

Booting from Knoppix reports the same amount of physical memory.

I have been doing some research and others say that the amount of memory that Windows can use is the 32-bit limit subtracted by the amount of system memory that's needed (including the amount of video memory from the video card). Which card is correct? I don't understand why these reported numbers are different from almost identical cards.

Answer : Problem: 32-Bit Memory Limitations & Video Card

I had a similar experience recently.  I had 4GB system memory fitted with an ATI Radeon 1900xtx 512MB video card and Windows could use ~3.2GB RAM (the BIOS reported 768MB had been appropriated).  When I upgraded the video card to an nVidia 8800 GTS 512MB the amount of memory usable by Windows decreased to 3GB (the BIOS reported 1024MB had been appropriated).

I haven't researched any further on this subject but have concluded that it is not necessarily the amount of video memory on the card that determines the amount of system memory appropriated from the full 4GB.