If everything is maxed out in games like Farcry 3 and Hitman, etc... I think the FPS you're getting are normal because these are demanding games and your hardware is simply not powerful enough.
The GTX-550Ti is not the fastest card around, this is an entry level gaming card, so don't expect wonders from it.
Look at the requirements for Farcry 3 and you do not meet the recommended or the optimal requirements. You just meet the minimum requirements so don't expect to max everything out:http://www.systemrequirementslab.com/CYRI/Requirements/Far-Cry-3/11465