Since the Beta period, I had been having tearing issues until a few days ago.
I fixed it by turning on 'Vertical sync.' You can turn it on under Video tab. It's the 4th from the top I think. I think it is turn off by default because my friend found that his vertical sync was also turned off and he never touches video settings.

If you turn on the v-sync, it will limit the fps to the frequency(hz) of your monitor set at Nvidia control panel. Even though I had 144hz monitor, because it was set at 60hz from Nvidia control panel, I was only getting 60hz max but I fixed it real quick by fiddling with the Nvidia control panel.

If it still tears.. I have no idea.