Hey guys, im sorta in stuck... At the moment im upgrading my system and was planning to go with a 570 and just sell my 6850, then I started thinking I should just buy another 6850 and crossfire them, it would end up saving me around $150 but im not sure if I will get the performance im after, will two 6850's outperform a 570 or a 580?

Firstly, name thread titles properly so people can search this stuff later on.

Secondly, the general rule is always choose one card over two, the reasons for this are:

1) Less heat, stability in games, when you CF or SLI you can have some issues with games like micro-stuttering.
2) Upgrade ability, if you buy one card now you can always buy another 570 down the road for cheaper, if you have two cards now you have no upgrade options.

This being said I think the CF 6850's will outperform a 570 but I wouldn't think it would be a lot.

If you end up going CF, make sure your PSU has the capacity to run them efficiently.

Would you look at what google found.. I can't believe it..

www.hardwareheaven.com/reviews/1080/pg16/inno3d-nvidia-geforce-gtx-570-review-gtx-570-vs-6850-crossfire.html

CF 6850's evidently out perform a single 570.

Go the CF 6850's given you already got one 6850. Didn't read OP properly

CF is more reliable than SLI in terms of it's functionality with games, especially new releases. 2x 6850 would be a good choice.

Well im planning to get a Silverstone Strider 750w.

Right now I have a Coolermaster xtreme 700w but it's not modular and Im really sick of the excess cables.

Im sure 750w would be enough to run the following
I5 2500k
Gigabyte superclocked 6850's in CrossfireX
4gb Corsair CM8 ram
2x 500gb HDD
60gb corsair SSD

You're already upgrading your entire system, get a GTX 570 and don't dead end upgrade.