Lag every few seconds on brand new ROG??

Nov 26, 2018
So, i just bought ROG Strix Scar II for a weeks.
Here the specs:
1. Intel i7-8750H 8th gen
2. Nvidia GTX 1060 6GB
3. DDR4 16GB RAM
4. Windows 10

For the first few days, i installed and play GTA V with Highest graphic settings and running very smoothly.
But few days later, when i start to play again, it start to lagging or fps drops every few seconds (4-7 seconds).
And it happens too for other games.

I've checked the thermal its normal like usual, about 70°C for CPU and 60°C for GPU.
Many forum with this similar problem says to update the GPU driver and check thermal issues. I mean its brand new high ends laptop, what should I do? Bring them to ASUS Service Center? Factory reset? Do i need to do that on brand new laptop?