previous attempt on 5800k posted here:

http://forums.vr-zone.com/hardware-depot/2...-completed.html

6800k is like a 5800k on steroid if u ask me. superb oc headroom plus d need for lower wattage lead to lower temp... one thing to note thou, i noticed even 6800k hybrid crossfire setup gives better figure in 3d benchmark but in games somehow it's more laggy than 5800k. it's more of driver issue imo. 

i've no resources on hd7750 hence i can't really comment on d performance boost from 6670 to 7750. but regardless hybrid crossfire or not, 7750 still significantly better than a 6670.