Just to answer the OP's question; when you look at a gpu's core bit size (128, 256, 320, 384), it determines the type of memory configurations possible on the card. There is a limited amount, it's just that you/we don't know how much it is, probably because we haven't taken to time to find out, and if we did, what would it matter? Most cards you will see are 256bit, which handles 256mb, 512mb, and 1gb. No real need to go higher at this point. 320bit cards have 320mb, and 640mb. 8800gtx and ultra are 384bit, hence the 768mb memory size.

As for the 1gb cards not performing well... http://www.fudzilla.com/index.php?option=com_content&task=view&id=4618&Itemid=40

11106

Athlon 64X2 6400+

8800gts (G80) 640mb @659/1000

4gb RAM

None of the above. It's a 4:3 ratio resolution, all the ones you listed are 16:9.RayvinAzn

1280x1024 is a 5:3 ratio (http://en.wikipedia.org/wiki/Image:Vector_Video_Standards2.svg).

Wikipedia is your friend, here's what you need. (hopefully you can read the chart correctly): http://en.wikipedia.org/wiki/Image:Aspect_Ratios_and_Resolutions.svg

1080i/p both have the same resolution.