thanks for the suggestion 
I think the biggest thing I notice in your render is the loss of texture detail on the marble and also the chair seat on the right hand side. Possibly the floor, sofa and tiles are quite lacking in tetail too, and the toolbox.
The shadow on the left is a little sharper on yours. With turbo render you would have reduced your render time by around 3 to 4 times to get the same result Iād guess, as like you say, I think I could have done with a little longer to get the same result on the shadow and glossy. Still, pretty close for 5x faster. The result I got would be achieved on your card in 5x faster than whatever you currently got