ASUS K46CB automatically disonnects and connects again from power source

Hi guys, so here is my problem.

I'm going to play intense game (such as NBA 2k15) in my laptop, i decided to take off my battery.
I load the game, after it start my computer suddenly shuts down without any warning.
So i decided to put my battery back, try to play again and it works fine.
However, still when in game suddenly super lag, and then back to normal again. This annoys me so much.

I check my power indicator at bottom it says Power4Gear High Performance,
suddenly change to Power4Gear Saving (The icon is battery only NOT plugged in), and then back to performance again. So i think this cause shutdown when no battery.

So i cant play with my battery plugged off (usually it is fine), now my power source suddenly plugged off and plugged in again, noted that this occurs when play games.

For temperature, it occurs between 60 MIN to 80 MAX.

Some solutions i tried:
1. Uninstall Power4Gear, no changes.
2. Format Windows, still occurs.
3. Change to balanced mode, still happens

Anyone knows why? Is it my laptop adapter or my PSU? Or anything else?
Noted that I decided to upgrade my ram to 8 GB, or is it because of ram?

My Laptop: ASUS K46CB
CPU: Intel Core i5 1.7 ghz
Graphic: GT 740M
RAM: 8 GB (Upgraded)


Kindly help thanks.