Try this out. http://extreme.outervision.com/psucalculatorlite.jsp
I tend to use it on a new build.
By the specs on the PSU you listed it has enough connectors for you to crossfire a few cards, so yes you can connect at least the one 7850. IDK what the power requirements are for your build though. Try the calculator I linked out. It'll tell you how much juice you need.