i can't run games like fifa 14,assassin's creed,splintercell back list and mortal kombat on my lenovo idepad z510 (intel i5 4th gen,6gb ram, 1tb hdd,8gb ssd,nvidia gt-740 m 2gb) during power is unplugged.
Laptops don't game well when they're not on AC power. That's just the way it is. If you want to do other things, unplug. If you want to game, plug in. There's no third option. You can set the power profile in control panel to high performance and tweak the advanced settings a little bit, which will help minimally, but mostly, it's hard wired behavior and can't be circumvented.
Gaming just requires too much power for battery function to handle.