Argonaut77 :
Why would I get worse performance? Sorry I am a noob when It comes to graphics cards and crossfire
When two cards (or one APU and a single GPU) are used in crossfire, the faster one is slowed down to match the slower one.
It seems that in this case the slower one would be over two times slower than the R7 265, making the configuration slower than it would be without crossfire/dual graphics. Not to mention all the issues crossfire has, like stuttering and bad compatibility with some games.