using a 32bit OS with 4gb ram and 1gb gfx

bigjimmyauk

bigjimmyauk

bigjimmyauk

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how will this affect things i know it will only use 4 gb but in which sense will it always use 3gb system ram and the full 1gb from gfx or am i totally missing the point somewhere tried google but didn't come up with much
 
sort of.. The 4gb of memory is allocated in two halfs, one half for the Windows and Drivers and the other half for applications. The application portition is controlled by Windows. This allocation can be changed but it not advisable. So it's not as limiting as it seems. However, as you state, memory mapping occurs on devices such as video cards which must allocate it's own address space in physical memory in order for the software to access it. So if you have a 512mb video card, 512mb of RAM will be made unavailable. It doesn't end there either, the BIOS will reserve memory for other mapped devices. It's a good enough reason to think again when buying a 1024mb video card if your not going to play at high resolutions.
 
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Most graphics cards dont need to reserve the entire memory pool, they simply reserve an overlay "windows" so the cpu / os can copy data to the GPU. That visible spot can be moved around so that windows can see all the graphics cards ram, but without wasting the memory address space of the computer as a whole.

Thats why you can SLI a pair of 1GB graphics cards and still have more than 2GB available ram for windows.

Before I switched to 64bit, I had 3.5GB available to windows with a 768mb 8800GTX.

Look how it used to work with AGP, you could specifiy how big the windows was in bios, and it was just fine to have a 64mb window with a 256mb card. The only problem these days is although PCI Express still uses a "window" into the GPU's ram, but its no longer possible to manually configure the window size, so its all down to the design of the GPU and drivers.
 
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