Tried it already, and crossfire still doesn't work for 6850's, but it may possibly work for newer cards.
nope doesnt work for me either 2xr9 270x toxic
SLI/Crossfire will be improved in an upcoming patch. *
nVidia and AMD cannot do it by themselves, so it makes sense this still doesn't work optimally. If you don't believe go to nVidia forums or AMD forums and search for other games that launched without SLI/Xfire support. Each have their part, it isn't one or the other.
When the patch drops that fixes this, the drivers/profiles will be in place to take "best" advantage is what this means.
The fact that this is based on BF4's Frostbite engine should mean it won't be to much of a problem for them. I shouldn't assume but I'd bet it's next patch when it comes.
*
https://twitter.com/JA_Wiebe/status/486951316149657600
There are a slew of graphic enhancements/updates incl. better crossfire support.
