So I've never done CrossFire before and I was curious if the specs of the two graphics cards are added together to find the final specs, or if it works differently. For instance, I have an R9 270x 4GB in my PC now, if I got a second one, it would seem that both of them together out-specs the R9 290x in most areas. So would it be better for me to just buy a second R9 270x or do a complete upgrade to an R9 290x?