I think, Passmark is not the correct benchmark against 870m
If you want you can look at this test http://www.notebookcheck.net/NVIDIA-GeForce-GTX-870M.107792.0.html
Where it is clear that backlog GTx 870m from the gtx 660ti by about 15 percent
thanks for the answer.
The most interesting that the GPU boss is not correctly evaluate 870m compared to the gtx 660.
look at this http://gpuboss.com/gpus/GeForce-GTX-870M-vs-GeForce-GTX-660
Now look at a comparison against the gtx 660 gtx 580...