2nd monitor acting up during games

[OfficialDavve]

Okay, so I bought this used 970 4gb graphics card a month back for a decent price but when I brought it back home and installed it etc I noticed something weird.
Whenever I launch any type of game, either borderless or fullscreen my second monitor will begin to flicker, that is if I have the game on my primary monitor.
My primary monitor is an Asus 144hz monitor and my secondary is some old Samsung Syncmaster.
My second monitor will have these small lines going up and down whenever there's a game on my primary one.
Otherwise the graphics card works great.
I do have the latest drivers installed and directx etc.
Thanks in advance.

 

[basroil]

It's not recommended to run a pair of monitors at different refresh rates, and likely there's a glitch caused by your strange setup. You can try doing a clean driver install and trying different output ports, one of those might work.

You can always disable the second monitor when gaming, and that will be 100% effective.