Going off bench marks, 9800GTX scores 928 on PassMark - G3D Mark, the GT 640 scores 1,283, about a 30% improvement, but still not much of an upgrade. http://www.videocardbenchmark.net/high_end_gpus.html 660ti on the other hand, 4,690.
I'm currently spending the holidays practising doing environment models. I thought I'd show this one - my third. It's 294 polygons with one 256x256 texture. *Updates below* enjoy
Adding transitional meshes could finalize the already great look for your gums/teeth: https://cdnb.artstation.com/p/assets/images/images/012/926/967/large/vadim-sorici-transitional-meshes-tutorial-teeth01-update.jpg?1537221551
http://www.minecraftforum.net/news/294-3d-character-skinning-utility/ making minecraft skin never been this easy! :D *edit apparently there are lot more skin editor .. and more realtime feedback if i use photoshop to edit