Several Game Lag and Heating Problem after Replacing Mobo

I was playing Farcry3 for a good 30-40 minutes after installing it, when suddenly my laptop start to freeze in the middle of the game, i thought it was just some minor glitch, but i tried to escape the freeze by pressing windows button, in hope the game minimizes and i can closed the window on the desktop. But !&&* i tried every single button on keyboard, and mouse it just didn't have any effects.

So i decided to force shutdown by pressing down the power button for several second. The laptop didn't shut down directly as usual, the screen is blank but i know the laptop is still running and the fan is even running excessively for several second. Then i press the power button again until its finally shut down.

However, when i try to turn it on again, it didn't work, simply didn't work, the HDD LED that usually blinks when i start the laptop doesn't blink at all. the only LED that blinks is the "lightbulp" Led and it was only for several second before it turned off again.

I have tried common troubleshooting by removing the power cord and pressing the power button for 30-60 second or so, but still doesn't have any effect.

My laptop is ASUS X455LJ, Core i3 5010u, Nvidia Gt 920m 1GB, 4 GB ram, it was only several months old and still under warranty.

My question is, what seems to be the problem? I'm suspicious it's the hard drive, however i've been suggested that it might be the VGA or even the Mobo as well.

However after bringing it to the authorized service center, they simply replace the whole Motherboard, everything went back to normal for daily computing and Multimedia.

BUT here comes the following issue, when i play several game titles which previously runs very smoothly (such as NFS Run, Fifa 15 and Just Cause 2), they all become very laggy and my laptop fan works harder than before. Ever since they replaced with new Mobo this happens but only when gaming.

I found this very peculiar since those games goes very smooth before the "Farcry incident' happened. Now that i remove Farcry and replaced the Mobo. How seems to be the problem now for my Laptop? i believe those games i mentioned are all eligible to be play for my laptop spec, no?

Please kindly help if you guys have any idea about my problem,

Thanks is advance!