Question for those who have GPU with 1GB VRAM

I have a question for those who have a video card with 1GB VRAM and has XP or Vista 32 bit version and 4GB System RAM.

Just how much System RAM recognized by the OS? To find out, press CTRL-SHIFT-ESC, click Performance Tab, Physical Memory and look under Total.

I am asking because I wonder if you have that much VRAM, just how much remaining address space is available for System RAM? A 32 bit OS has up to 4GB address space. Out of those 4GB, 1GB would be robbed by the VRAM. The other 0.5 to 1GB would be robbed by other peripherals. You may only have 2 to 2.5 GB left for the System RAM.

 

Windows Vista 32 bit recognized somewhere between 3.2 and 3.5GB of system RAM. It is under Windows Vista 64 bit that 4GB+ can be recognized. The video RAM is a different issue. If you're referring to the VRAM being shared by Vista then you don't have anything to worry about, because as long as your graphics card has 1GB of dedicated video RAM then Windows will not "rob" your system memory. It might show under Windows Vista "Shared System Memory" a certain amount, but if you have enough dedicated VRAM and look above that under "System Video Memory" it'll show "0" in use. That means that Windows has allocated a certain amount of system RAM to be used for video RAM in case it ever needs it. (Which is never if you have 1GB of dedicated VRAM)

In other words you have nothing to worry about, because that allocated system memory is not actively being shared with your graphics card and you'll still have your system RAM for use.

 

I am not worrying about Video Card has to share System RAM with the motherboard. I am worrying that the video card 1GB VRAM will take 1GB address space which is not the same as taking away 1GB from the System RAM. Address space /= System RAM.

All 32 bit OS has 4GB address space. This address space will have to be shared with everything installed in the computer. And that includes the soundcard, hard drive, network card, chipset, modem, video card, system RAM etc. That is why you only see 3 to 3.5 GB System RAM available in a 32 bit OS because 0.5 to 1 GB of address space has been used by all the peripherals in the computer. The rest of the address space that is not being used by the peripherals is available for the System RAM to use.

Now, those computers that have 3 to 3.5 GB System RAM available don't have 1GB VRAM in the system. But if the computer has it, the amount of address space available for the System RAM would be even lower and I want to know just how much lower.

 

He's not talking about shared memory. Since the 32-bit OS can address maximum 4GB (2^32 = 4 294 967 296) of memory for the whole system (VRAM, RAM, Soundcard RAM), it needs to preserve some space for the graphics cards and anything else that have memory needed to be addressed. That's why 32-bit OS can only recognise ~3GB.