IMHO it sounds right, crossfire is giving your cpu more work to do that is why you are seeing a higher usage on the cores with it enabled and your cpu must be struggling to keep up with your GPU's in crossfire hence the reason why you don't get 99% usage on both cards.
Your options now are, try to overclock your cpu further, sell one of your cards, or sell your mobo, ram and cpu and go sandybridge.
Maybe ask Santa to bring you something nice
Your options now are, try to overclock your cpu further, sell one of your cards, or sell your mobo, ram and cpu and go sandybridge.
Maybe ask Santa to bring you something nice

well looks like i will need to find some money have to say though i was rather shocked how good a single card runs this game :-0 