How much are you planning to spend in total? You should look out for the December edition of "Best Graphics Cards for the Money" by none other than Tom's Hardware. The Radeon 6900 series are also coming out soon, I suggest you hold out on your purchase until the complete lineup of graphics cards of the year have come out.
Before reading the article, many readers may still think that efficient and compatibility of CrossFire is not well.In fact, I can tell you that after several years development,CrossFire technology is gradually improving, the user need not worry about these history problems. this test can verify this fact .
In this test, I deliberately put performance of HD6850 CF with performance of single card in order to facilitate comparison.You can see that after set up HD6850 CrossFire,the improvement of performance is very huge,It most games performance are better than GTX580and part at least on par with that of HD5970 and even has a slight advantageThis proves the efficiency of current CrossFire is very good,It absolute can bring better gaming experience to players.
Just has good performance but the power consumption is high will not make you be satisfied.But after this test,I can say that you need not worry about this problem any more.either standby or running high-load game, HD6850 CrossFire perform better than other flagship products.
If you have budget in mind then 2xGTX460 in SLI is a good combo, Also the GTX570 is looking like a very well-priced card.
Dont get a GTX 480 unless you have found a really good deal on one, the GTX580 directly replaces the 480 and uses less power and produces less heat and yet gives more FPS. The Radeon cards are hard to comment. If you can wait till next week (or even a couple of days time) the 69XX series will come out.
The reviews for the 6950 and 6970 are out. The 6970 performs at par with the GTX 570, while the 6950 has a segment all to itself. Given that the 570 costs less than the 6970, while coming with great stuff from nVidia like PhysX, CUDA, and 3D Vision, I'd say "None of the above" to your choices and get a 570 instead. Reasons:
The 480 is too much of a power hog and produces a lot of heat.
At this point, the 58xx series are retired in favor of the 69xx series, so the 5870 is also out.
The GTX 2xx series are outdated (There isn't any GTX 270, maybe you mean a 275).
The 6870 is OK since it has all of AMD's new technology and architectural advancements built in, but if your budget allows it, Go for the 6970 or 6950. Get 2 of each if your budget and PSU allows it.