Who said there is a GTX570 with 3Gb VRAM, there is not.
The only card with 3Gb VRAM to my knowledge is the GTX580 version.
This is definitively the card to have
for the time being!
(because as I mentioned in previous posts, I believe we have to wait for two generations of GPUs to come in order to see real performance with this game).
You can see the performance of this card thanks to Tuckie's great work (download the high quality video but be careful, the 1080 quality is 340Mb )
FPS test video on switching from GTX275 to GTX580
~S~