The addition of a CrossfireX GPU to the 785 would definitely offer better graphics performance, that's why people do it.
when you say "crossfirex gpu to the 785", are you talking about a "hybrid" crossfirex
capable card, and if so the "people" that you refer to that do it, can they be reached for questioning because i have both thr "785" and the "4670" and the 785 does not hybrid crossfirex interact with anything except the 2400pro, the 3450, and the 3470
contrary to what some diagrams on this site, other tech sites and more than one mobo. man.'s site says. hell, amd themselfs state that the 785 chipset does not support hybrid crossfirex "at this time." this is in email response to tech support questions, not in advertisements (which is just the opposite). if you could put me in touch with these people so i can gain the advantages you speak of, i could use the added graphics capability. if you were just blowing smoke up some guys usb hole because you like to see your words in type, then please disregard this reply.