Hm, when I played BF3 on my thuban, I saw all the threads being used, not fully loaded, but used. Usage was jumping in every thread from 33% to 60-80%. That's on 1080p with ultra settings with 6970@stock. So topping out at 4 threads is not really true
By the way, it ran 55-60fps all the time, and I mean all the time.