↑ That's my problem.
I used one monitor without the problem for about year, and I bought the same thing.
There was no problem at 4 days ago. (actually, I set monitors this day)
But now, there is a problem as you can see that video.
I reinstalled graphic driver, and replaced DP cable to HDMI cable. (I read it on the internet)
It never changed...
I also read it might be a graphic card's problem.
But I don't know how I can fix it.
Now I'm using one monitor to pull out new monitor's cable. Pretty sure. One monitor, no problem.
How can I fix this problem?