I just bought an i7-950, asus sabertooth x58 mobo, 6gb ram at 1866 speed, the Tom's hardware recommended case of 2010, and my monitor runs at 1920x1680. I have a 5770 in my posession but i'm not sure if i should crossfire another 5770 or if i should buy a 68xx, crossfire 6850's, 5870 or any other card under $350 (max i'm gonng spend). Will another 5770 give me the same performance as a single newer card and save me money. I want to spend as least amount as money as possible but i want to be able to play Rift at max settings or close to max settings with good fps. As you can see, i'm a little confused on what would be the best decision.
You'd be better off with one 5870 or one 69xx series card if you have the money. Most benchmarks with these cards beat two 5770s at all resolutions. These are all cards within your $350 range. Most gaming benchmarks show the 68xx series performing lower than the 5870s (though your 3dMark vantage score will be better - if people really care about synthetic benchmarks). You can get a 6970 for right around $379 and $359 after rebates, while 6950s are around $300. As the drivers improve for these the 6970 should clearly outperform any of 5xxx-series cards with the exception of the 5970 (2 GPU card). Just me, but I'd skip the 68xxs altogether with your budget. Further, you can pick up a single 5870 for between $220-$300 these days; definitely an excellent choice.
Although you've posted in the ATI section, I just want to suggest the Gigabyte 1GHz edition GTX 560Ti. It's performance is on par with that of a 570, but at a $270 price point. It's probably the best bang for your buck at the time.
If you look at the Guru3D review below, you'll see an increase of around 20-50FPS over a 5770 in every single game tested. Bear in mind that these games are mostly tested with high detail, AA, etc. It also scores around 10,000 points higher in 3DMark Vantage.
If you happen to still be looking (I see this thread is a few weeks old, but maybe others can get info from it), you can get a single 2gb 6950 for $249.99 on newegg atm, (which is at the same pricepoint as a gtx 560 ti) and unlock it to a 6970, which will surpass anything else you can get at that price point except a 5970. The 560 ti is intended to compete with the 6950, whereas the 6970 competes with the 570. The 580 is the best single card, but the 6970s crossfired scale so well that they can almost catch up with the performance of 580s in Sli, but for 1/2 the price. And in regards to the Benchmarks posted by PudgyChicken, you can see that the SOC 560 ti can compete with a stock 6970 in half the tests, but OC'd a bit it should pull ahead slightly.
Thanks for the advice guys, I went with a 6970 and it's running everything just fine. I figure if i need to improve my graphics performance in the future i will SLI another one on there. Thanks for the feedback.