Actually there is a GPU called either a X800XL or a X850XL (depending on the card maker I think), that is a lot cheaper than the X800XT or 850XT, and it performs very well indeed, the only thing is, they seem rare to find.
The AGP aperature doesn't use any system RAM per se, it merely sets a maximum amount of AGP system memory that the AGP bus will use.
This is the way it works I think... You are heavily into an action scene in a game and the video card is running out of room to process the textures, so the AGP kicks in and starts using system ram to process the textures via the AGP bus.
I read somewhere that in game, it's mainly the textures that get processed on the AGP bus.
In the case of a very fast video card with lots of ram, you really dont want to use the system memory via AGP because it's not nearly as fast as the DDRIII video ram and will actually slow your game down. Some people tweak their settings to disable the AGP memory usage altogther, thus, reportedly increasing performance.
Some games may well use in excess of the card's memory however, so unless you really know your stuff, leave the AGP memory enabled.
I have found that a AGP aperature setting of 128mb works faster in some benchmarks on my rig than a setting of 256mb. But this hasn't been resolved, and certainly depends on your configuration.
With 1024mb of system ram total, and 256mb allowed for maximum AGP memory, the worst case is that if your video processing is so overloaded that it is actually using the maximum available AGP memory, your game only has, at the most, about 630mbs of ram to operate in, as your op sys etc is using around 120mb plus.
I wouldn't worry to much about the setting, setting it for 128mb will probably be safe to say the least, but if you do have some issues with Frame Rates, then you might try and alter it in a controlled way so you can monitor the result/effects of the change.
Remember, setting the aperature alone doesn't use any system ram, it only sets a maximum allocation for AGP memory. This is quite a different animal from the typical onboard video card RAM allocation, which actually DOES reserve the system ram for the onboard graphics chip, if any. Ram that is reserved for onboard video cannot be used by the rest of the system and is removed from the total count at the PC's boot screen.
I think I need a new prop for my hat .......
Edited by Congo, 13 April 2005 - 02:32 AM.