Does 1 Gb graphics card and 4Gb RAM make the system memory 5gb ?

32-bit Windows has an address space - not memory limit - of 4GB.

With a 1GB graphics card - the graphics memory and system BIOSes are included in the 4GB address space - only around 2.75GB of the address space is left for RAM, so that is all that can be used.

In round numbers XP, Vista and Windows 7 32-Bit Versions of the Operating System can only address 4GB. Does not matter how much memory you have installed 4GB is the max. From that max your video card has XXXMB of ram on the card so that limits the operating system to 4GB minus the cards XXXMB of memory.

In addition other hardware also takes away additional amounts of memory (usually a small when compared to the video card)

and the remaining memory (address space) is available for Windows XP, Vista or Windows 7 OS and your applications.

So that 4th GB thru 16 GB of ram you installed or will install goes unused on a 32-Bit OS. Does not matter what the BIOS reports or what the OS shows as installed memory it still limited to that 4GB address barrier.

A link to the white paper titled "Gaming Performance Analysis" by Corsair

Memory Inc. provides a good clear explanation of how a video card effects

the amount of available memory in your PC.

See: http://www.corsair.com/_appnotes/AN804_Gaming_Performance_Analysis.pdf

Intel Chipset 4 GB System Memory Support

http://www.dcomputer.com/ProInfo/support/support/mainboard/4GB_Rev1/4GB_Rev1.pdf

Vista Users with SP1 now report how much physical memory installed on your computer:

See: Windows Vista SP1 includes reporting of Installed System Memory (RAM):

http://support.microsoft.com/kb/946003

RAM, Virtual Memory, Pagefile and all that stuff:

Basic information about the Virtual Memory implementation

in 32 bit versions of Windows 2000, XP, 2003 Server etc.

http://support.microsoft.com/kb/555223

J W Stuart: http://www.pagestart.com