Playing games causes my other display to lag

[Hurre111]

So if i watch stream or video on my another display, then i go to play games, the other display starts lagging very badly. Like its fps is 1-2 or something. If i go to task manager and put the game to use only 3 cores, then the lag is gone on another display but my fps in game is bad. What can cause this problem? Even if the other display only has discord app on, i can see the lag when i speak and the green mark around my profile picture lights on way too late and laggy. So its like everything lags when i play games.

I have tried following fixes but they haven't worked:

Windows 10 reinstall
Windows theme settings to default
Display driver reinstall and geforce experience uninstall
vsync settings on/off
Borderless/fullscreen both have same issue


Specs
asus PG248Q 144hz (DP) and 60hz samsung monitor (hdmi)
Intel i5 4670k @4.3GHz
MSI Gtx 970
8gb ram

 

[cwli1_]

Try each screen by itself.