I would advise you to overclock your CPU..
Not because you can, but because it is seriously lacking for CFX and SLi configs.
Do you have a decent CPU cooler?
agree with you bud!
overclocks your cpu by 15-20% should get rid of any real bottlenecks
and also instead of buying another hd 7850 why dont sell it and buy a single powerful card like a gtx 670 or hd 7970