stutter with dual monitor setup

[Gloft]

hello i am using benq xl2411z and another crappy 60hz monitor and when i play league of legends with both of them connected i get serious stutter it almost makes the game unplayable.
Using gtx 970 with amd fx 8350 8gb ram

ps:this happens only on league of legends

 

[Gloft]

i just realized this is probably the wrong forum for this question as it has to do with league of legends only i am going to post on league forum if anyone knows a fix or a reason please post

 

[getochkn]

Both connected but only playing on 1 screen? Have you tried windowless window mode or windowed mode?

 

[Gloft]

Both connected but only playing on 1 screen? Have you tried windowless window mode or windowed mode?

yes i play in fullscreen windowed(borderless) i have the other connected when i remove the cable of the second monitor from the gpu i stoped stuttering

sry for bad english
ps:if it matters at all my second 60hz monitor has only vga input and its connected to gpu with DisplayPort(male) to VGA(female) adapter