andy5174 :
3GB, lol. I knew it since vista came out.
2^32 = 4,294,967,296 bytes = 4GB.
Generally, I use: 4GB - 512MB (motherboard) - GPU RAM = Avaliable system RAM. So a 512MB card generally leaves 3.25-2.75GB of free RAM for general use.
PAE uses the X86's native 36-bit processing mode to extend the limit to 2^36 = 68,719,476,736 bytes = 64GB.