What video card should I get -minimum- with an i7/x58/6gig ddr3?

[rohan23]

you have to keep in mind that that is the 512MB version. i think that the 1GB 4870 with its ddr5 might actually surpase the 260 gtx core 216

No, it was compared to the 1GB version. I doubt the 512MB version is around $300.00.
By the way, DDR5 doesn't have much to do with it. The number refers to the latency. There isn't a huge difference in performance on the GDDR (Graphic Double Data Rate) by latency alone. There are many other factors that play into the speed of the card.