It say there is 256mb version and 512mb version. Option 1: You could add memory, i guess if you have the chip and some machine to weld on the chip. Option 2: Call nvidia to ask if you can add more memory to your chip, but ( my bet ) they will charge you like twice the price you pay. Option 3: Sell it and buy a better card. Option 4: Why you want 512mb on a 7300GS for ?
the board will use up to 256 of your system memory to make it 512.
that dont make the card any faster and actually i think the tc cards are crappy because you are using your system memory for part of your video memory.
i tried to play nfsmw on a 6200 with tc and the delay was bad you would turn then blink and the game would then start to turn.
This is an example of how they figure 512mb (in Dell's case). The card that came with my system was a 7300LE Turbo Cache 256mb. It is portraited as a 256mb card but it is not. This is the breakdown of that configuration:
dedicated ram 128mb
shared ram 128mb
promoted as 256mb but it isn't
512mb comes from taking additional ram from your system to get that figure depending how much total ram you have
So Dell promotes this as a 256mb video card and what you actually get is:
a 128mb card with a 64bit interface
takes 128mb of system ram to say it's 256mb
can take up to an additional 256mb of system ram
so your losing 384mb of your system's ram to get this 512mb figure