i cant believe this is true, gfx card memory hogs total memory address

[anelka9]

http://www.dansdata.com/askdan00015.htm

please read this guys and tell me what you think.

It doesnt make sense cause i have 2GB ram now, 1.6GB available, 276mb taken by Winxp and 130mb by applications. The math is right but i have a 512MB gfx card (Pci-e).
I based this on my task manager in winxp 32bit.

AGP aperture size was present in older cards with older boards tat you can set an aperture eg, 256 or 512mb to allow how much memory the graphics card can address via AGP. But this isnt valid anymore in PCI-e!

he is respectable and everyone else says it but i need clarification on his theories.

 

[Fraggable]

Yes, it's true and commonly known. No 32-bit OS can address more than 4GB of memory total, no matter where in your system it's located or what its use is.

Hoever, if you have say 3 X 1GB sticks in your system you will lose dual-channel mode, wheras if you have 4 sticks you maintain dual channel mode and should still see about 3.25GB of memory. With as cheap as DDR2 is anymore, I'd say it's work just buying the 4th stick.

 

[alaricljs]

He's right. Total addressing space on 32bit OS's is 4GB. So subtract a whole *pile* of stuff from 4GB and you get the total addressable RAM space.

This is the manual of the PDSME+ a Supermicro Server/Workstation mobo. On page 2-7 (or 27th page) is a chart of all the different subtractions from addressable memory.

I don't think Supermicro would get this one wrong.

 

[zephyrprime]

He's mostly right but I think he is wrong on some parts. And it's not a theory either it's a plain fact. Video memory does use up memory space and in a 32bit system, this is a big problem because it causes you to not be able to use all your ram. However, I think he is doing some of the math wrong. I seem to recall that on my system with 256mb of video memory, the memory is actually mapped 3 times onto the system memory space - once for each display output (2 dvi + 1 s-video). So the problem is actually worse than he states.

But like he says, these problems should be gone with 64bit systems. And even if the video memory space is mapped into the lower 4GB memory space, it shouldn't subtract on the available memory in a 64bit system because memory can be mapped beyond the physical amount of memory installed. To clarify, he talks about some of the memory in an 8GB system being taken away because of the virtual memory mapping but the system can get around that by just mapping some of the 8GB of memory beyond the 8GB threshold. The memory can just be remapped all over the place.

Also, I think the AGP aperture is still functional even in a pci-e card. The "aperture" is really just a lame way to implement a crude form of virtual memory for the video card using system memory. Only DX10 implements true video card virtual memory and makes the agp aperture obsolete.