goto
www.notebookcheck.com and see framerates for those games.
http://www.notebookcheck.net/Lenovo-IdeaPad-Y580-20994B...
7580 is a monster. "...Nonetheless, performance in games is remarkable. Every game tested is more than playable on High settings and some can even run at a respectable 30 Hz on 1080p Ultra settings, most notably Skyrim and Arkham City. Battlefield 3 continues to be one of the most demanding PC first-person shooter titles, but even that is playable at 40+ FPS on High settings....Players who opt for a native 1366x768 display on the Y580 should have no problems maxing out details for all major titles released thus far. ..."
edit: I forgot "Also can anyone tell me what will the 16 GB SSD improve ? " The 16GB SSD is used as a cache. The system tries to put the most frequently used disk data on the SSD so that when you read it it will appear in 150 to 300 microseconds instead of the 5000 to 12000 microseconds (5 to 12 milseconds) of your spinning disk drive. If the system guesses right then boot and application load times will be better. If it guesses wrong then you have no real improvement over a spinning drive.
Personally I'd leave the slot used by the 16GB SSD empty, then replace with a 240GB SSD that you can use as your system disk. Having your entire system on SSD takes the guesswork out, and a 128GB MSATA ssd is only $100 now and a 240GB MSATA SSD is only $200 now. Look on amazon or newegg for an MSATA SSD. Something like a crucial M4 in MSATA format. MSATA cards install in the same slot used by the 16GB ssd (whch is a 16GB MSATA drive), but you'd use it as a disk instead of as a cache.