I just bought this laptop (Lenovo Ideapad Y50).
I'm playing games such as Battlefield 4 (upto date DLC) and WatchDogs. Even though I set battery manger to High Performance mode game doesnt works well unless I put back the Battery charger power cord to ON.
On Discharging my FPS in Battlefeld 4 (64slots server) - 30fps On Batter charging mode FPS 60fps both in HIGH Settings.
NVIDIA cards and Intel chips are all sporting power saving features these days, and your symptoms will primarily have to do with the NVIDIA card's performance level when taken off AC power. Regardless of the user's preferences, these cards will automatically drop to a lower performance level when running on battery power.
It is possible to force them to maintain top performance while on battery, but registry hacks will need to be employed, and it will drain your battery in double quick time.
There's a long post about it here. By the time you get to the bottom of page 5 you'll have the registry values you need to solve the issue.
On your Control Panel -> Power Options there are many Power Plans. If your power plan is switched to Balanced, on discharging you will have reduced performance. You can switch it to High Performance Plan in order to have 100% Performance while charging and discharging. However Activating High Performance Plan May Reduce your Battery Life.
That's normal behavior in those laptops. They have a very power consuming graphics card and usually a big CPU in case of yours, that for being able to work properly they need the power charger connected. I have the Y510p and its the same as for yours.
