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system RAM Display Adapter Memory?

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If I have 512 mb RAM then does this mean my .exe can be 512 mb? if I have 128 mb memory on my graphics card then does it mean I can load .bmp pictures until I hit 128 mb?

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I dont exactly know what you are asking. Have you ever heard of a "swap-file"? If the system runs out of "real" mems, it uses the harddrive as "pretend ram".

And even if your 512mb ram, 512mb program idea was true, you have not taken into accont the fact that windows uses at least 100mbs of stuff, and you have other programs running too.

Just dont worry about it.

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Question #1: No. All other software running on your system needs memory too. Technically you have a pagefile where things which don't fit in memory at the moment will be written to disk then "swapped" back into memory when needed, but this is slow.

Question #2: No. The screen requires a portion of video memory, and perhaps other things which are specific to the card or driver do as well. I believe the driver is responsible for managing the video memory, and does so in a similar manner as the OS kernel manages system memory. When there isn't enough room for the current texture in video memory it will be kept in system memory... and if there isn't enough room in system memory then eventually the bitmap will be swapped out to the pagefile.

Please correct me if I'm wrong on this you graphics gurus out there.

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Look into virtual memory.
Every program is alocated some very large piece of memory (4Gb or more).
This memory does not actually exist anywhere until the OS allocates physical storage for it.
This means that only the memory your program uses from its 4Gb is actually reserved in physical storage on the computer.
Now, since there is limited RAM, the OS can allocate storage off the swap file on the HD too.
So memory that hasn't been used recently will not be in RAM if some other piece of data needed to be accessed.

The graphics card drivers do something similar with GPU ram. They try to load everything onto the card.
Remember that this means vertex data, shader programs, and images.
But, when there is no room on the card, the data stays in the drivers virtual memory (in RAM, or worst case on disk).

When you hit the GPU ram limit, AND are using everything that you told the driver to load, you will see massive performace loss.
This is because the information keeps getting swapped on and off the card.
When you hit the usable physical RAM limit, AND are using everything you loaded into ram,
you will see even worse performace drop since the data is now being swapped to and from the disk drive.

You can have very large programs and see minimal performace drop. If you dont
use all the data all the time, but you want to load it all at once
you dont see the same performce drops. For example, you can load a very very large level, with lots of textures,
and if you only use some textures in each part of the level, and only need to
access some of the level data (ie what is around the player)
then you dont have the problems you would if you tried to access all the
level data every frame.

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Sometimes when I load more graphics and init more variables then my program freezes. Even Ctrl-Alt-Delete usually doen't work (sometimes does) and I have to reboot. Would the freeze be caused by going over the limit of Graphics Ram or System Ram ?

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